Determine and Analyze Central Ideas
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7th Grade Reading › Determine and Analyze Central Ideas
Read the passage and answer the question.
When people talk about renewable energy, they often focus on the type of technology—solar panels, wind turbines, or hydropower. The passage explains, however, that the bigger question is what these sources replace. Electricity made by burning coal or natural gas releases carbon dioxide, a greenhouse gas that traps heat in Earth’s atmosphere. In contrast, solar and wind generate electricity without releasing carbon dioxide during operation, so switching to them can lower overall emissions.
The passage also develops a second idea: renewable energy can be expensive at first, but it may save money over time. Building wind farms or installing rooftop solar requires upfront spending for equipment and construction. Yet once installed, the “fuel” for wind and sunlight is free, and maintenance costs can be predictable. Over many years, that can make the total cost competitive with fossil fuels, especially when fuel prices rise.
Finally, the passage notes that renewables require planning. Because wind and sunlight vary, power companies may add batteries, connect to larger regional grids, or keep some flexible power plants available. These steps help ensure electricity is reliable while emissions decrease.
Question: How is the idea that renewable energy can save money over time developed across the passage?
By comparing upfront costs with long‑term factors like free fuel and predictable maintenance, showing how total costs can become competitive.
By listing different renewable technologies and explaining how each one works in detail.
By arguing that fossil fuels will disappear soon, making renewables the only possible choice.
By focusing mainly on how batteries store energy and ignoring costs altogether.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Renewable energy passage focuses on one central idea: renewable energy can save money over time despite high initial costs. Development traced: Paragraph 2 introduces idea ("renewable energy can be expensive at first, but it may save money over time"), provides supporting evidence (upfront costs for equipment/construction acknowledged), then contrasts with long-term benefits (free "fuel" from wind/sun, predictable maintenance costs), concludes with comparison ("total cost competitive with fossil fuels, especially when fuel prices rise"). Development shows progression from acknowledging initial expense through explaining ongoing savings to final cost comparison. Option B correctly traces this development: "By comparing upfront costs with long-term factors like free fuel and predictable maintenance, showing how total costs can become competitive." Option A incorrect—lists technologies but passage doesn't detail how each works when developing cost idea; Option C incorrect—passage doesn't argue fossil fuels will disappear soon; Option D incorrect—batteries mentioned briefly in different context, not focus of cost development. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "renewable energy" topic but "renewables save money over time" specific idea about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (free fuel from sun/wind is detail supporting broader cost-saving idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Development analysis requires following specific idea through passage, noting introduction, evidence provided, examples given, and conclusions drawn—not just identifying idea exists but showing how author builds and supports it systematically.
Read the passage and answer the question.
In the late 1800s and early 1900s, many Americans moved from farms to cities for factory jobs. The passage explains that industrialization changed how people worked. In factories, workers often performed one repeated task instead of completing an entire product. This system increased production, but it could also be exhausting and dangerous, especially when machines lacked safety guards.
The passage develops a second idea: these working conditions helped lead to labor organizing. As factories grew, workers realized that one person complaining to a boss rarely changed anything. Groups of workers formed unions to negotiate for shorter hours, safer workplaces, and better pay. Strikes sometimes stopped production and pressured factory owners, although strikes could also lead to conflict with police or replacement workers.
The passage adds that new laws and public attention gradually changed some conditions. Reports about child labor and injuries persuaded some lawmakers to set age limits and require safer equipment. While problems did not disappear, the passage shows how changes in work, collective action, and government responses were connected.
Question: Which option best summarizes the passage objectively?
The passage explains how factory work increased production but created harsh conditions, and it describes how unions and laws developed in response.
The passage is mainly about how machines work and why cities are more exciting than farms.
The passage proves that factory owners were cruel and that strikes were the only fair solution.
The passage lists every law that ended child labor and completely fixed workplace safety.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Industrialization passage (250 words). Two central ideas developed: Central Idea 1: Industrialization changed how people worked through factory system. Developed through: Paragraph 1 explains shift from farms to factories, describes new work patterns (repeated tasks vs. complete products), notes increased production but also exhaustion/danger. Central Idea 2: Poor working conditions led to labor organizing and eventual reforms. Developed through: Paragraph 2 explains union formation and collective action (strikes, negotiations), Paragraph 3 describes resulting laws and public attention leading to changes (age limits, safety requirements). Connection: Idea 1 establishes conditions that prompted Idea 2's responses—cause and effect relationship showing how industrial changes created problems that sparked organized responses and reforms. Objective summary must capture both ideas factually without opinion or evaluation. Option A provides objective summary: "The passage explains how factory work increased production but created harsh conditions, and it describes how unions and laws developed in response." Uses neutral reporting language ("explains," "describes"), captures both central ideas (factory conditions AND organized responses), appropriate length, no personal opinion or evaluation. Option B adds opinion/evaluation ("proves," "cruel," "only fair solution"); Option C misidentifies central ideas focusing on minor details; Option D overstates content and completeness. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "industrialization" topic but "industrialization changed work patterns" and "poor conditions sparked organizing" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (repeated tasks, safety guards are details supporting broader ideas—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Objective summary requires neutral language reporting what text says, not reader's opinions about whether changes were good/bad, fair/unfair.
Read the passage and answer the question.
Before a drought is obvious, it often begins quietly. The passage explains that drought is not only “no rain.” It is a long period when water supply falls below what people and ecosystems need. Scientists track rainfall, soil moisture, river levels, and snowpack in mountains because melting snow feeds many rivers in spring and summer.
A second central idea is that drought affects different parts of society in connected ways. Farmers may struggle to irrigate crops, which can reduce harvests and raise food prices. Cities may limit lawn watering or car washing to conserve water. Hydroelectric dams can produce less electricity when reservoirs drop, which may require power companies to use other energy sources.
The passage also describes how communities respond. Some regions build water-storage systems, repair leaking pipes, and encourage drought-tolerant landscaping. Others reuse treated wastewater for irrigation or industry. The passage concludes that understanding drought measurements helps leaders plan responses that reduce harm to both people and the environment.
Question: Which option best summarizes the passage objectively?
The passage lists every drought in history and explains exactly when the next one will happen.
The passage describes how drought is measured using several indicators and explains how drought affects agriculture, cities, and energy while prompting different responses.
The passage argues that droughts are always caused by careless farmers and could be stopped if everyone watered less.
The passage is mostly about how to build hydroelectric dams and why lawns should be banned.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Drought passage (300 words). Three central ideas developed: Central Idea 1: Drought is complex phenomenon measured through multiple indicators. Developed through: Paragraph 1 defines beyond "no rain," explains measurement methods (rainfall, soil moisture, river levels, snowpack), shows scientific approach to understanding. Central Idea 2: Drought affects different sectors in connected ways. Developed through: Paragraph 2 traces impacts across agriculture (crop irrigation, harvest reduction), cities (water restrictions), energy (hydroelectric production), shows interconnected effects through society. Central Idea 3: Communities can respond with various strategies. Developed through: Paragraph 3 describes responses (storage systems, leak repair, drought-tolerant landscaping, water reuse), emphasizes planning based on understanding. Objective summary must capture all central ideas neutrally. Option A provides objective summary: "The passage describes how drought is measured using several indicators and explains how drought affects agriculture, cities, and energy while prompting different responses." Uses neutral language ("describes," "explains"), captures main ideas (measurement, impacts, responses), appropriate length, no opinion/evaluation. Option B adds false causation and opinion (careless farmers, could be stopped); Option C misidentifies content (dams, lawn bans); Option D overstates (every drought, exact predictions). Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "drought" topic but "drought measured through multiple indicators," "drought affects sectors in connected ways," "communities can respond strategically" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (snowpack measurement is detail supporting broader measurement idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Objective summary captures essence without adding interpretation, maintaining text's factual tone while including all major concepts developed.
Read the passage and answer the question.
In many cities, summer nights are getting warmer faster than nearby rural areas. One reason is the “urban heat island” effect. Dark roofs and roads absorb sunlight during the day and release that heat slowly after sunset, keeping neighborhoods warmer. Tall buildings can also block wind, which would otherwise carry heat away. Scientists measure this by comparing temperatures from weather stations placed in downtown areas and in parks or farmland outside the city.
City planners are not limited to simply noticing the problem; they can reduce it. Planting more trees adds shade and cools the air through evaporation from leaves. Some cities replace black asphalt with lighter pavement that reflects more sunlight, and they encourage “cool roofs” made from reflective materials. These changes can lower local temperatures and reduce the need for air conditioning.
The passage also explains why this matters for people’s health and budgets. Hotter nights make it harder for bodies to recover from daytime heat, increasing the risk of heat illness, especially for older adults and people without reliable cooling. Higher air-conditioning use can raise electricity bills and strain power grids during heat waves. By combining temperature data with design changes, cities can protect residents and manage energy demand.
Question: Which option best states two central ideas of the passage?
Cities are always hotter than the countryside because the sun shines more strongly on urban neighborhoods.
The passage describes what causes the urban heat island effect and explains ways cities can reduce its impacts on health and energy use.
Urban areas have more tall buildings than rural areas, and wind patterns are different in cities.
Air conditioning is the main reason cities stay warm at night, and power grids cannot handle heat waves.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Urban heat island passage (300 words). Two central ideas developed: Central Idea 1: Urban heat island effect causes cities to be warmer than rural areas. Developed through: Paragraph 1 explains causes (dark surfaces absorb heat, buildings block wind), provides scientific measurement method (comparing urban vs. rural weather stations), development traced from phenomenon through causes through measurement. Central Idea 2: Cities can reduce heat island impacts through planning and design changes. Developed through: Paragraph 2 identifies solutions (trees for shade/cooling, lighter pavement, reflective roofs), Paragraph 3 explains why this matters (health risks from hot nights, energy costs, power grid strain), development shows problem in Idea 1 leads to solutions in Idea 2 and their importance. Both ideas developed across passage with evidence. Connection: Idea 1 establishes problem (what causes urban heat), Idea 2 provides response (how cities can address it), Paragraph 3 shows why both matter (health and energy impacts)—together provide complete understanding of urban heat phenomenon, solutions, and significance. Option C correctly identifies both central ideas: "describes what causes the urban heat island effect and explains ways cities can reduce its impacts on health and energy use." Options A, B, and D each contain only supporting details (A: tall buildings and wind patterns are specific causes, not central ideas; B: incorrect detail about sun shining more strongly plus supporting detail about air conditioning; D: two supporting details elevated to central status) or factual errors, missing the two main concepts the passage develops comprehensively. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "urban heat" topic but "urban heat island effect causes cities to be warmer" and "cities can reduce impacts through design" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (dark roofs absorb heat is detail supporting broader heat island idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Common mistakes include confusing supporting details with central ideas, missing one of multiple central ideas, or failing to see how ideas connect across the passage.
Read the passage and answer the question.
When students search online, it can feel like the first result must be the best. The passage explains that search engines rank pages using many signals, such as how many other sites link to a page and how closely the words match the search. These signals can help find useful information quickly, but they do not guarantee accuracy. A popular page can still contain mistakes, and a well-written headline can make weak evidence sound convincing.
A second central idea is that readers can take specific steps to judge credibility. The passage suggests checking the author’s expertise, looking for dates to see whether information is current, and comparing claims across multiple reliable sources. It also recommends reading beyond the first paragraph to see whether the article provides evidence, such as data, quotations, or links to original research.
The passage concludes that online research is a skill. Instead of trusting rankings alone, students should combine an understanding of how search results are created with careful evaluation of sources.
Question: How are the two central ideas developed and connected in the passage?
The passage explains how search rankings work, then shows how that knowledge leads to strategies for evaluating credibility.
The passage lists random internet facts and ends by warning students not to use the internet at all.
The passage focuses only on author biographies and does not mention search engines.
The passage argues that the first search result is always accurate and should be used without checking.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Online search passage (200 words). Two central ideas developed: Central Idea 1: Search engine rankings don't guarantee accuracy. Developed through: Paragraph 1 explains how rankings work (links, word matches), then pivots to limitation ("do not guarantee accuracy," popular pages can have mistakes, headlines can mislead). Central Idea 2: Readers can take specific steps to evaluate credibility. Developed through: Paragraph 2 provides concrete strategies (check author expertise, dates, multiple sources, evidence), builds systematic approach to evaluation. Connection between ideas: Idea 1 establishes problem (rankings ≠ accuracy), Idea 2 provides solution (active evaluation strategies), Paragraph 3 synthesizes showing research as skill combining understanding of search mechanics with critical evaluation—knowledge from Idea 1 enables strategies in Idea 2. Option A correctly traces this development and connection: "The passage explains how search rankings work, then shows how that knowledge leads to strategies for evaluating credibility." Shows progression from understanding system to applying that understanding for better evaluation. Option B incorrect—doesn't list random facts, doesn't warn against all internet use; Option C incorrect—does mention search engines prominently; Option D incorrect—argues opposite of passage's main point about not trusting rankings alone. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "online searching" topic but "rankings don't guarantee accuracy" and "readers can evaluate credibility" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (checking author expertise is detail supporting broader evaluation idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Connection analysis shows how understanding one idea (how rankings work) enables effective response (evaluation strategies)—ideas build on each other.
Read the passage and answer the question.
When a new disease appears, public health workers try to understand how it spreads. The passage explains that contact tracing is one tool for slowing outbreaks. If a person tests positive, trained workers ask where that person has been and who they were close to. Those contacts can then be notified, tested, and advised to stay home to avoid spreading the illness further.
The passage develops a second idea: contact tracing depends on trust and good communication. People may hesitate to share information if they fear blame or job loss. To improve cooperation, health departments may protect privacy, provide clear explanations, and connect people with resources such as food delivery or temporary housing so they can isolate safely.
The passage also notes limits. Contact tracing works best when case numbers are manageable and testing is available quickly. During very large surges, health departments may focus on high-risk settings like nursing homes or schools. The passage concludes that contact tracing combines science, logistics, and community support.
Question: Which statement best describes how the central idea about trust is developed in the passage?
It is developed by listing the names of every disease that has ever existed.
It is developed by claiming that trust is unnecessary because tracing works perfectly without communication.
It is developed by explaining why some people may not share information and by giving examples of steps health departments take to increase cooperation.
It is developed by describing how to perform laboratory tests in a hospital.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Contact tracing passage focuses on central idea about trust and communication. Central Idea development traced: Paragraph 2 introduces idea ("contact tracing depends on trust and good communication"), explains why people hesitate (fear blame, job loss), provides solutions health departments use (protect privacy, clear explanations, connect with resources like food delivery/housing), shows how these steps "improve cooperation." Development progresses from identifying trust as requirement, through explaining barriers to trust, to describing specific actions that build trust. Option A correctly traces this development: "It is developed by explaining why some people may not share information and by giving examples of steps health departments take to increase cooperation." Shows both problem (why people hesitate) and solution (department actions) aspects of trust development. Option B incorrect—doesn't list disease names; Option C incorrect—not about lab procedures; Option D incorrect—claims opposite of passage's point about trust being necessary. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "contact tracing" topic but "contact tracing requires trust" specific idea about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (food delivery is detail supporting broader trust-building idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Development analysis requires following specific idea systematically: introduction of concept, explanation of challenges, presentation of solutions—complete arc showing how idea is built throughout passage.
Read the passage and answer the question.
In the early days of space exploration, rockets were built to do one main job: escape Earth’s gravity. The passage explains that launching anything into orbit requires enormous speed, which demands large amounts of fuel. Carrying all that fuel makes rockets heavy, so engineers use stages—separate sections that drop away when their fuel is used up. Staging reduces weight during flight and makes reaching orbit more efficient.
The passage also develops the idea that modern space missions depend on careful planning beyond the launch. Satellites must be placed in specific orbits depending on their purpose. A weather satellite may need to pass over many parts of Earth, while a communications satellite might stay above the same region. Mission planners calculate paths, fuel needs for small adjustments, and the timing of launches so rockets can meet their targets.
Finally, the passage notes that new technology is changing costs. Reusable rocket boosters can return to Earth and be flown again, reducing the need to build a new booster for every mission. The passage suggests that staging, orbit planning, and reusability work together to make space travel more practical.
Question: What are two central ideas of the passage?
Space travel is easy now, and fuel is no longer important for rockets.
Reaching orbit requires engineering solutions like staging, and successful missions also rely on precise orbit planning and improving costs through reusability.
The passage is mainly about the history of astronauts and the food they eat in space.
Rockets are painted white to reflect sunlight, and most satellites take pictures of storms.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Space exploration passage (250 words). Three central ideas developed: Central Idea 1: Reaching orbit requires engineering solutions like staging. Developed through: Paragraph 1 explains gravity challenge, fuel requirements, staging solution (dropping sections to reduce weight), efficiency gains. Central Idea 2: Successful missions depend on precise orbit planning. Developed through: Paragraph 2 describes different orbit needs (weather vs. communications satellites), planning requirements (paths, fuel, timing), mission-specific calculations. Central Idea 3: Reusability is reducing costs. Developed through: Paragraph 3 introduces reusable boosters, explains cost reduction (no need for new booster each mission), connects to practicality. Connection: all three ideas address making space travel feasible—staging solves weight problem for launch, orbit planning ensures mission success, reusability addresses cost barrier. Option B correctly identifies central ideas: "Reaching orbit requires engineering solutions like staging, and successful missions also rely on precise orbit planning and improving costs through reusability." Captures all three main concepts passage develops. Option A contains only supporting details (white paint, satellite pictures); Option C contains false information (space travel not described as easy, fuel still important); Option D misidentifies topic focusing on astronauts/food not mentioned. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "space exploration" topic but "staging enables reaching orbit," "orbit planning ensures mission success," "reusability reduces costs" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (weather satellite example is detail supporting broader orbit planning idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Multiple central ideas work together showing different aspects of making space travel practical—engineering, planning, and economics.
Read the passage and answer the question.
Many people think of microbes only as germs, but the passage explains that microbes also play helpful roles in the human body. In the digestive system, communities of bacteria help break down certain foods and produce vitamins. Scientists have found that different diets can change which microbes thrive, which may affect how efficiently the body uses nutrients.
A second central idea is that the balance of microbes can influence health in more than one way. The passage describes research suggesting that some microbes help train the immune system to recognize harmful invaders. When the balance is disrupted—after a strong course of antibiotics, for example—some people may experience digestive problems because beneficial bacteria have been reduced along with harmful ones.
The passage adds that researchers are still learning, so simple answers are rare. While probiotic foods and supplements may help some people, the passage emphasizes that results vary and that medical advice is important for serious conditions.
Question: Which statement best identifies the topic and a central idea of the passage?
Topic: antibiotics; Central idea: antibiotics should never be used because they always harm the body.
Topic: immune cells; Central idea: immune cells are microbes that live in the stomach.
Topic: microbes in the human body; Central idea: helpful microbes support digestion and can affect health by interacting with diet and the immune system.
Topic: vitamins; Central idea: vitamins are the only reason people need bacteria.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Microbes passage example demonstrates topic vs. central idea distinction. Topic: microbes in the human body (broad subject—what passage is about). Central Idea 1: Helpful microbes play beneficial roles, especially in digestion. Developed through: Paragraph 1 counters "only germs" misconception, explains digestive bacteria roles (breaking down food, producing vitamins), notes diet affects which microbes thrive. Central Idea 2: Microbe balance affects health in multiple ways including immune function. Developed through: Paragraph 2 describes immune system training by microbes, explains disruption effects (antibiotics example), shows broader health connections beyond digestion. Option C correctly identifies topic and central idea: "Topic: microbes in the human body; Central idea: helpful microbes support digestion and can affect health by interacting with diet and the immune system." Shows broad topic (microbes in body) and specific assertion about that topic (they help digestion and affect health through various interactions). Option A narrows topic to vitamins, overstates as "only reason"; Option B wrong topic (antibiotics are example, not topic), extreme false claim; Option D confuses immune cells with microbes. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "microbes" topic but "helpful microbes aid digestion" and "microbe balance affects health" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (vitamin production is detail supporting broader helpful role idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Topic identification requires finding broadest subject (microbes in human body), while central ideas are specific claims passage makes about that topic (helpful roles, health effects).
Read the passage and answer the question.
In many school cafeterias, food waste is a daily problem. The passage explains that waste happens for several reasons: students may have short lunch periods, they may be required to take items they do not want, or they may be unfamiliar with certain foods. When edible food is thrown away, schools lose money and more trash ends up in landfills.
A second central idea is that reducing waste requires changes in routines, not just reminders. Some schools schedule recess before lunch so students arrive hungry and have more time to eat. Others let students choose portions or start “share tables” where unopened items can be left for other students. The passage notes that these strategies can cut waste while still following health rules.
The passage also describes what can happen to food that cannot be saved. Composting turns scraps into soil that can be used in gardens, returning nutrients to the ground instead of sending them to a landfill. The passage concludes that combining prevention, safe sharing, and composting can reduce waste and costs.
Question: Which option best states two central ideas of the passage?
Lunch periods should be eliminated, and all cafeteria food should be replaced with packaged snacks.
Students dislike vegetables, and composting is too complicated for schools to attempt.
The passage is mainly about gardening tools and the best soil for growing tomatoes.
Food waste in cafeterias has multiple causes, and reducing it involves practical routine changes and systems like sharing and composting.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). School cafeteria waste passage (250 words). Two central ideas developed: Central Idea 1: Food waste in cafeterias has multiple causes. Developed through: Paragraph 1 identifies causes (short lunch periods, required items students don't want, unfamiliar foods), explains consequences (money loss, landfill waste). Central Idea 2: Reducing waste requires systematic changes in routines and infrastructure. Developed through: Paragraph 2 describes routine changes (recess before lunch, portion choice, share tables), Paragraph 3 adds infrastructure solution (composting), emphasizes "combining prevention, safe sharing, and composting." Connection: Idea 1 establishes problem with multiple causes, Idea 2 provides multi-faceted solutions addressing those causes—comprehensive approach matching problem complexity. Option B correctly identifies both central ideas: "Food waste in cafeterias has multiple causes, and reducing it involves practical routine changes and systems like sharing and composting." Captures problem (multiple causes) and solution (routine changes plus systems) that passage develops. Option A contains unsupported claims (students dislike vegetables) and contradicts passage (composting described as feasible); Option C suggests extreme non-solutions not in passage; Option D completely misidentifies content. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "food waste" topic but "cafeteria waste has multiple causes" and "reduction requires systematic changes" specific ideas about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (share tables are detail supporting broader systematic change idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Two central ideas work together: understanding multiple causes (Idea 1) leads to multi-pronged solutions (Idea 2)—comprehensive treatment of issue.
Read the passage and answer the question.
Recycling is often described as a simple habit, but the passage explains that it is part of a larger system for reducing waste. When paper, glass, and certain plastics are collected and processed, fewer raw materials have to be taken from forests, mines, or oil fields. Using fewer raw materials can also reduce pollution created during extraction and manufacturing.
A second central idea is that recycling works best when communities do more than toss items in a bin. The passage describes how people must sort materials correctly, because food residue or mixed materials can contaminate a whole batch. It also notes that local governments and companies need factories that can process recyclables and buyers who will use the recycled material to make new products.
The passage includes specific examples to support these ideas. For instance, aluminum can be recycled repeatedly, and making aluminum from recycled cans uses far less energy than making it from raw ore. The passage concludes that recycling is most effective when individual choices and community infrastructure work together.
Question: Which choice best distinguishes a central idea from a supporting detail in the passage?
Central idea: Recycling is part of reducing waste and conserving resources; Supporting detail: Making aluminum from recycled cans uses far less energy than making it from raw ore.
Central idea: Aluminum can be recycled repeatedly; Supporting detail: Recycling reduces the need for raw materials.
Central idea: Sorting is unnecessary; Supporting detail: Contamination can ruin a batch of recycling.
Central idea: People should recycle more; Supporting detail: Recycling is always easy in every community.
Explanation
Tests determining two or more central ideas in informational text (main points passage develops, not topic or supporting details), analyzing how ideas develop over course of text (introduction, support through evidence and examples, connections), and providing objective summary (capturing central ideas factually without opinion). Central ideas are specific main points passage develops about topic: Topic is broad subject (climate change, renewable energy, recycling—what text is about generally, one or two words), central ideas are specific assertions or concepts about topic (not just "climate change" but specific ideas: "Human activities cause global warming" and "Climate change produces wide-ranging effects on environment and economy"—specific main points text develops, complete thoughts). Recycling passage example shows distinction between central ideas and supporting details. Central Idea 1: Recycling is part of larger system for reducing waste and conserving resources (Paragraph 1 develops this broad concept). Central Idea 2: Recycling works best with proper sorting and community infrastructure (Paragraph 2 develops this implementation concept). Supporting details include specific examples: aluminum can be recycled repeatedly (supports Idea 1), making aluminum from recycled cans uses less energy than from ore (supports Idea 1 about conservation), contamination can ruin batch (supports Idea 2 about proper sorting). Option B correctly distinguishes: "Central idea: Recycling is part of reducing waste and conserving resources; Supporting detail: Making aluminum from recycled cans uses far less energy than making it from raw ore." The central idea is the broad concept about recycling's role in conservation; the supporting detail is specific example about aluminum energy savings that illustrates this broader point. Option A reverses this—treats specific detail about aluminum as central idea; Option C includes opinion ("should recycle more") not in passage and false detail; Option D presents contradictory ideas not from passage. Determining and analyzing central ideas: (1) Read complete passage identifying topic (broad subject—what's this about?), (2) distinguish central ideas from topic (not "recycling" topic but "recycling reduces waste/conserves resources" specific idea about topic—what main points does passage make?), (3) identify all central ideas (longer passages often have 2-3—find each main concept passage develops), (4) note supporting details vs. central (aluminum saves 95% energy is detail supporting broader conservation idea—levels matter), (5) trace development (how is each central idea introduced, supported with evidence, explained through examples?—follow idea across passage), (6) understand connections (how do multiple central ideas relate building complete understanding?—causes and effects, problems and solutions, different dimensions of topic). Key skill is recognizing hierarchy: central ideas are main concepts passage develops thoroughly, supporting details are specific facts/examples that illustrate these broader concepts—aluminum example supports conservation idea but isn't itself the main point.