When scientists study fossils, they are not only hunting for dinosaur bones. Fossils also record details about ancient climates. For example, seashells found high in the mountains show that an area was once under water. Layers of pollen trapped in mud cores can reveal which plants once dominated a region.

Researchers read the chemistry of fossil shells and teeth to estimate past temperatures. Tiny differences in the elements that make up these materials change with the warmth of the water or air. By comparing these patterns across many sites, scientists can map climate shifts over thousands of years. One set of fossils might show a long stretch of warm, wet weather; another might capture a sudden cold snap.

Understanding how climate changed before people kept records helps researchers test their ideas about how the climate system works today. By connecting the past to the present, scientists improve their predictions about future changes and how communities can prepare.

What role does paragraph 3 play in the passage?

Two years ago, the school library had plenty of shelves but few visitors. Long rows of tall bookcases made the room feel cramped. Tables were fixed in place, and signs reminded students to keep quiet. Teachers said the space did not fit group projects or clubs.

The redesign team started by lowering some shelves to open sightlines. They added moveable tables and soft chairs that could be rearranged quickly. A corner became a makerspace with simple tools and craft supplies. Wall outlets and charging carts made it easier to use laptops for research.

After the changes, student visits doubled in a semester. Coding and poetry clubs found regular meeting spots, and the makerspace hosted weekly challenges. Teachers booked the collaboration room for debates and small seminars. Circulation went up too, especially for nonfiction tied to class units.

The library did not abandon quiet reading; it added ways to learn together. By starting with the problem and testing solutions, the school turned a silent room into a flexible hub for learning.

How does paragraph 1 contribute to the development of ideas in the passage?

Paragraph 1: Twice each year, many people reset their clocks for Daylight Saving Time (DST). In spring, an hour is lost, and in fall, an hour is gained. The practice, first adopted during the 20th century, was meant to shift daylight into evening hours. Yet every time the change arrives, conversations flare: Is it helpful? Is it harmful? Before weighing those questions, it helps to understand what DST is and why it became part of everyday life.

Paragraph 2: Supporters argue that lighter evenings encourage outdoor activity and reduce electricity use and car accidents. Some businesses report more customers when the sun sets later. Critics respond that the time change disrupts sleep, especially for children, and that modern energy savings are small. They point to studies showing short-term spikes in accidents and health issues after the switch. These competing claims explain why the practice continues to spark debate.

Paragraph 3: In recent years, several regions have proposed staying on one time all year. Lawmakers, scientists, and community groups compare data and consider local needs. Whether or not policies change, the discussion shows how habits, health, and economics all factor into decisions about timekeeping.

How does paragraph 1 contribute to the author's overall purpose?

Paragraph 1: Animals have many ways to share information, but honeybees use a signal that is both unusual and precise: the waggle dance. Inside a dark hive, a returning forager moves in a figure-eight pattern while vibrating her body. The dance is not for show; it gives other bees clues about where to find nectar and pollen.

Paragraph 2: The direction of the waggle path tells followers which way to fly relative to the sun, and the length of the waggle tells them about the distance. This code lets a bee describe a food source she has seen miles away, even if the hive mates have never been there. Scientists learned to read the dance by filming hives and comparing the movements to the locations of flowers.

Paragraph 3: For example, if a forager waggles at a slight angle to the left of straight up, followers fly slightly left of the sun's position. If she waggles for a longer time, they travel farther. After watching, several bees exit together and head to the same clump of trees the dancer visited. This concrete example shows how the dance turns movements into a map other bees can follow.

What role does paragraph 3 play in the passage?

Paragraph 1: Around the world, tons of edible food are thrown away each day. That waste represents lost money, wasted water and energy, and missed chances to feed people in need. Communities are exploring practical steps to reduce what ends up in the trash, especially from stores, restaurants, and school cafeterias.

Paragraph 2: One approach is donation. When a grocery store has too much bread or slightly bruised fruit, it can safely send those items to a food pantry. Donation keeps food in the human food chain. It helps families stretch their budgets, and it prevents perfectly good items from being buried in landfills.

Paragraph 3: Another approach is composting. In contrast to donation, composting is for scraps that people will not eat, such as peels and coffee grounds. These leftovers are collected and allowed to break down into rich soil. While donation directly feeds people, compost nourishes gardens and farms. By highlighting these differences, communities can choose the right solution for each kind of leftover.

How does paragraph 3 contribute to the development of ideas?

Paragraph 1: For years, a vacant lot at the corner of Maple and Third sat full of weeds and litter. Neighbors avoided walking past it, and parents warned children to stay away. The lot became a symbol of neglect in a small town that otherwise prided itself on tidy streets.

Paragraph 2: A group of residents decided to act. On Saturday mornings, they picked up trash, pulled invasive plants, and built simple raised beds. With a small grant from the city, they added two benches and a gravel path. Local students painted birdhouses, and a retiree donated young trees. Slowly, the space changed from a problem to a place people wanted to visit.

Paragraph 3: Today the pocket park offers shade, flowers, and a safe spot to sit. It also offers proof that small projects can reshape a neighborhood. By describing the results, this final section shows why the effort mattered: it invites readers to see how cooperation can turn an eyesore into an asset.

What is the role of paragraph 3 in developing the ideas of the passage?

Paragraph 1: Daylight Saving Time (DST) is the practice of moving clocks forward in warmer months to make better use of evening daylight. The idea is that more light after school and work can reduce energy use and give people extra time outdoors. By defining the practice and its purpose, the paragraph prepares readers for the debate that follows.

Paragraph 2: Supporters point to brighter evenings that reduce the need for artificial lighting and may make streets feel safer. Critics, however, argue that changing clocks disrupts sleep and doesn't save as much energy as once believed. Some communities have even studied accident rates to see whether the switch helps or harms.

Paragraph 3: Whether regions keep or drop DST, the decision hinges on weighing convenience against health and safety. Each place must judge if the benefits of later light outweigh the costs of shifting schedules.

How does paragraph 1 contribute to the author's overall purpose?

Paragraph 1: When our town's vacant lot became a community garden, it wasn't only about planting seeds. The project started as a way to use neglected space, but it quickly grew into something bigger: a place where neighbors could learn about food, share tools, and make decisions together. The organizer's purpose was to show how a simple idea can bring people together.

Paragraph 2: The garden produced more than tomatoes and herbs. It created regular chances for teens to volunteer, for elders to teach pruning, and for families to try new recipes. Before long, the space hosted weekend workshops on saving water and building raised beds. These examples support the idea that shared work can strengthen a neighborhood.

Paragraph 3: Still, the garden wasn't effortless. Watering schedules clashed with jobs, summer heat wilted seedlings, and a debate over the compost bin's location lasted weeks. These challenges didn't erase the gains; instead, they revealed the patience and planning required to keep the garden thriving.

Paragraph 4: By season's end, the lot looked different, but so did the people who met there. The garden became proof that small steps—kept up over time—can change both a landscape and a community.

How does paragraph 3 contribute to the author's overall purpose?

Paragraph 1: Our school cafeteria throws away bags of mixed trash each day, much of it recyclable or compostable. Students and staff say they want to reduce waste, but at lunch the bins fill quickly with leftovers, napkins, and containers all jumbled together. The principal asked a student team to design a better system.

Paragraph 2: The team mapped where students lined up, where they sat, and how they exited. They found that the single trash can at the door created a traffic jam and encouraged people to toss everything together. The students proposed three stations—compost, recycling, and landfill—placed along the natural path out of the room, with simple pictures above each bin.

Paragraph 3: After a two-week trial, the cafeteria cut its landfill trash in half, and the exit line moved faster. Volunteers noticed fewer spills and less confusion once the stations were in the right order.

Final sentence: In the end, a few well-placed bins and clear cues turned good intentions into everyday habits.

What role does the final sentence play in the passage?

Some riders think short trips around the neighborhood are too simple to require a helmet. Researchers wondered whether distance or speed changes the risk of head injury. To find out, a public health team reviewed accident reports from several cities and interviewed cyclists about their habits.

The data told a clear story. Riders who wore helmets, regardless of how far they traveled, were less likely to suffer head injuries in crashes. The protective effect appeared in slow, residential areas as well as on busy streets. In interviews, cyclists described near misses where a helmet shielded them from branches, doors, or a patch of gravel.

No safety gear can prevent every injury, and the study could not measure every factor, such as flashing lights or bike lane quality. Even so, the results support a simple choice: wearing a helmet is a practical step that reduces risk on short rides and long ones alike.

What role does paragraph 2 play in the passage?