Middle School Science Quiz: Plan Temperature Investigation

20 questions · exam conditions

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Plan Temperature InvestigationQuestion 1 of 20

A student is planning the insulation investigation: Which material insulates best—foam, plastic, or fiberglass?

They will wrap identical cups with each material, fill them with the same volume of hot water, and measure temperature over time. Which list includes the most necessary materials/equipment to complete the investigation and collect temperature vs. time data?

Thermometer, identical containers/cups, foam/plastic/fiberglass, timer/stopwatch, measuring cup or graduated cylinder, lids or plastic wrap, notebook/data table

Ruler, magnets, balance scale, protractor, and graph paper only

Thermometer and foam only, because insulation is the only variable that matters

Microscope, petri dishes, and goggles, because temperature is best measured by looking at water molecules

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Middle School Science Quiz

Middle School Science Quiz: Plan Temperature Investigation

Practice Plan Temperature Investigation in Middle School Science with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Plan Temperature Investigation, giving you a quick way to practice the rules, question types, and explanations that matter most for Middle School Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A student is planning the insulation investigation: Which material insulates best—foam, plastic, or fiberglass?

Thermometer, identical containers/cups, foam/plastic/fiberglass, timer/stopwatch, measuring cup or graduated cylinder, lids or plastic wrap, notebook/data table (correct answer)
Ruler, magnets, balance scale, protractor, and graph paper only
Thermometer and foam only, because insulation is the only variable that matters
Microscope, petri dishes, and goggles, because temperature is best measured by looking at water molecules

Question 2

A class is investigating: How does the mass of water affect the time it takes to heat up? They will heat water from 20°C to 80°C on the same hot plate. Which set of variables is identified correctly for this investigation?

Independent: heating time; Dependent: mass of water; Controlled: target temperature (80°C).
Independent: mass of water; Dependent: time to reach 80°C; Controlled: starting temperature, hot plate setting, container type. (correct answer)
Independent: hot plate setting; Dependent: starting temperature; Controlled: mass of water.
Independent: container material; Dependent: mass of water; Controlled: time to reach 80°C.

Question 3

A student wants to study cooling: Does the temperature difference between hot water and the room affect cooling rate? The room is 20°C. The student will test starting water temperatures of 60°C, 70°C, and 80°C using identical insulated containers and the same water volume.

Which measurement plan best allows the student to determine and compare cooling rates?

Measure the temperature once at the start and once after 30 minutes, then decide which cooled fastest based only on the final temperature.
Measure and record the water temperature in each container every 5 minutes for 30 minutes, keeping the containers in the same location, then calculate cooling rate using $\Delta T/\Delta t$ for each trial. (correct answer)
Measure the room temperature every minute, but do not measure the water temperature until the end.
Measure the temperature at random times whenever it seems like the water has changed a lot, and write down only the biggest change you notice.

Question 4

A student is testing the question: Does temperature difference ( $\Delta T$ ) affect cooling rate? The room is $20\,^{\circ}\mathrm{C}$ . The student will use three identical insulated containers, each with the same volume of water, starting at $60\,^{\circ}\mathrm{C}$ , $70\,^{\circ}\mathrm{C}$ , and $80\,^{\circ}\mathrm{C}$ . What is the best measurement plan?

Measure the water temperature once at the start and once after 30 minutes, then choose the container with the biggest drop as the fastest cooling rate.
Measure the room temperature every 5 minutes, but do not measure the water temperature until the end.
Measure the temperature of each container every 5 minutes for 30 minutes, record all values in a data table, and calculate cooling rate for each using $\Delta T/\Delta t$ over the same time interval. (correct answer)
Measure the temperature of only the hottest container every minute for 30 minutes, then assume the others cool the same way.

Explanation: This question tests understanding of how to plan a complete temperature investigation by designing a procedure with proper variable control, selecting appropriate materials and equipment, and planning systematic measurements. Planning an investigation requires: (1) clarifying the research question (identifying what you want to find out: "Which material insulates best?" or "How does thickness affect cooling?"), which determines your variables (independent = what you'll change, dependent = what you'll measure); (2) designing procedure (step-by-step instructions ensuring fair test: prepare trials with independent variable values, set controlled variables constant, measure dependent variable systematically); (3) selecting materials and equipment (thermometers for temperature, timer for time intervals, appropriate containers and insulation materials, heat source if needed); (4) planning measurements (when to measure: intervals like every 30 min, or at specific times like 1 hr and 2 hr; what to measure: temperature in °C, time in minutes; how many: at least 3-5 measurements to show pattern); and (5) organizing data collection (prepare data table with columns for time/independent variable and rows for measurements, ready to record during investigation). For cooling rate investigation: Planning "Does starting temperature affect cooling rate?" requires: (1) prepare three identical insulated containers (same material, thickness—control insulation), (2) fill each with same volume water (500 mL controlled) at different starting temperatures (60°C, 70°C, 80°C—independent variable creating different ΔT from room temp), (3) seal all and place in same room (ambient temp constant), (4) measure temperature every 5 minutes for 30 minutes (all containers measured at same times), (5) calculate cooling rate for each (ΔT/Δt: temperature drop per minute), (6) compare rates (predict: larger ΔT cools faster initially—Newton's law of cooling, rate proportional to temperature difference). Choice C is correct because it properly plans measurements at appropriate intervals (every 5 minutes provides sufficient data points), measures all containers systematically, records all values for analysis, and calculates cooling rate using proper formula (ΔT/Δt) over same time interval for fair comparison. Choice A measures only at start and end (missing intermediate data showing cooling pattern), cannot determine if cooling is linear or curved, and "biggest drop" doesn't account for different starting temperatures (80°C to 50°C is bigger drop than 60°C to 40°C, but both cooled 30°C). Choice B measures room temperature (already known: 20°C) instead of water temperature, missing the actual data needed to calculate cooling rates. Choice D measures only the hottest container, assuming others cool the same way (invalid assumption—cooling rate depends on temperature difference), missing comparative data. Proper measurement plan requires: regular intervals (5 min appropriate for 30 min total), all containers measured at same times (fair comparison), complete data set for each container (calculate individual rates), same analysis method for all (ΔT/Δt over same interval)—this systematic approach reveals how initial temperature difference affects cooling rate according to Newton's law of cooling.

Question 5

Investigation question: Which material absorbs heat faster—metal, plastic, or wood?

A student has equal-mass samples of each material, a heat lamp, a thermometer, and a timer. Which procedure best tests heat absorption fairly?

Place all three samples the same distance from the heat lamp for the same amount of time; measure and record each sample's temperature at the start and then every minute for 10 minutes; keep distance and lamp setting the same. (correct answer)
Heat the metal sample for 10 minutes, the plastic for 5 minutes, and the wood for 2 minutes; then measure the temperatures once and compare.
Place the samples at different distances from the lamp so they all warm up quickly; measure temperature only at the end.
Put the samples in different rooms with different starting temperatures; measure after 10 minutes and decide which absorbed heat fastest.

Question 6

A student tests insulation materials (foam, plastic, fiberglass) by filling identical cups with the same hot water and measuring temperature over time. Which controlled variables are most important to keep the test fair?

Same cup size/type, same water volume, same starting temperature, same location/room conditions, same time intervals for measuring (correct answer)
Different cup sizes so each material fits better, and different starting temperatures to see a wider range of results
Same insulation material each time, but change the water volume to make results more interesting
Same room conditions, but allow different starting temperatures and different volumes for each cup

Question 7

A student is testing which insulation material keeps water warmest. They plan to wrap cups with foam, plastic, and fiberglass and record temperatures over time.

Which change would most improve the reliability of the results without changing the investigation question?

Repeat each insulation test 2–3 times and average the temperature data for each material. (correct answer)
Use a different starting temperature for each material to see a wider range of results.
Test foam in the morning, plastic at noon, and fiberglass after school in different rooms.
Change both the insulation material and the thickness at the same time so there are more differences to compare.

Question 8

A student plans a cooling-rate study: Does temperature difference ( $\Delta T$ ) affect cooling rate? The room is $20^\circ\text{C}$ . The student will start water at $60^\circ\text{C}$ , $70^\circ\text{C}$ , and $80^\circ\text{C}$ in identical insulated containers. What measurement plan best matches this investigation?

Measure the temperature once after 30 minutes and decide which started hottest cooled fastest.
Measure temperature every 5 minutes for 30 minutes for each container, record all values in a time–temperature table, and calculate cooling rate (change in temperature divided by time) for each starting temperature. (correct answer)
Measure the room temperature every 5 minutes but do not measure the water temperature until the end.
Measure the mass of the containers every 5 minutes to find the cooling rate.

Explanation: This question tests understanding of how to plan a complete temperature investigation by designing a procedure with proper variable control, selecting appropriate materials and equipment, and planning systematic measurements. Planning an investigation requires: (1) clarifying the research question (identifying what you want to find out: 'Does temperature difference affect cooling rate?' which determines your variables (independent = starting temperature/ΔT, dependent = cooling rate)); (2) designing procedure (step-by-step instructions ensuring fair test: prepare trials with independent variable values, set controlled variables constant, measure dependent variable systematically); (3) selecting materials and equipment (thermometers, timer, identical insulated containers, water); (4) planning measurements (when to measure: frequent intervals like every 5 min for 30 min; what to measure: temperature in °C over time; how many: multiple points to calculate rate); and (5) organizing data collection (prepare data table with columns for time and temperature per starting point, ready to record and calculate rates). For cooling rate investigation: Planning 'Does starting temperature affect cooling rate?' requires: (1) prepare three identical insulated containers, (2) fill each with same volume water at different starting temperatures (60°C, 70°C, 80°C), (3) seal and place in same room (20°C ambient), (4) measure temperature every 5 minutes for 30 minutes, (5) calculate cooling rate for each (ΔT/Δt), (6) compare rates (larger ΔT cools faster per Newton's law). Choice B is correct because it properly plans measurements at appropriate intervals and duration, includes recording in a time-temperature table, and specifies calculating cooling rate which directly matches the dependent variable for this investigation. Choice A is wrong because it plans inadequate measurements by only measuring once after 30 minutes, missing intermediate data needed for rate calculation, and doesn't record systematically; Choice C omits measuring the water temperature regularly, focusing on room temp which is controlled not dependent; Choice D measures wrong variable (mass instead of temperature), violating the investigation focus. Complete investigation planning checklist: (1) QUESTION: does ΔT affect cooling rate?; (2) HYPOTHESIS: yes, proportional; (3) MATERIALS: thermometers, containers, timer, water, data table; (4) VARIABLES: independent (starting temp), dependent (cooling rate), controlled (volume, ambient temp, insulation); (5) PROCEDURE: fill, heat to starts, measure over time, calculate rates; (6) DATA: table (time | temp per start), schedule every 5 min; (7) SAFETY: hot water handling; (8) TIMELINE: 1 hour. Example complete plan: Question: ΔT vs cooling rate; Variables: independent = start temp (60,70,80°C), dependent = rate, controlled = 500mL, same room; Materials: as above; Procedure: (1) prepare containers, (2) heat water to starts, (3) measure every 5 min for 30 min, (4) record, (5) calculate rates; Safety: use tongs; Timeline: 45 min per setup—produces reliable data.

Question 9

Investigation question: How does insulation thickness affect cooling rate?

A student has the same type of foam insulation and can wrap identical cups with 1 layer, 2 layers, or 3 layers. They will put the same volume of hot water in each cup and measure temperature over time. Which plan correctly identifies variables and avoids changing more than one independent variable?

Change both the insulation material (foam vs. fiberglass) and the number of layers at the same time to get more results quickly.
Independent: number of foam layers; Dependent: temperature change over time; Controlled: cup type, water volume, starting temperature, room conditions, and measurement times (correct answer)
Independent: final temperature after 2 hours; Dependent: number of layers; Controlled: thickness and starting temperature can vary
Independent: room temperature; Dependent: foam layers; Controlled: water volume only

Question 10

Investigation question: How does the mass of water affect heating time?

A student heats 100 g, 200 g, and 400 g of water from $20^\circ\text{C}$ to $80^\circ\text{C}$ on the same hot plate. They want results that are reliable. Which improvement best increases reliability without changing the question?

Repeat each mass trial 2–3 times, record the heating times, and calculate the average time for each mass. (correct answer)
Use a different hot plate for each mass so all three can be heated at the same time.
Change the target temperature for each mass so the times are not too similar.
Stop timing when the water starts to steam instead of using a thermometer to check $80^\circ\text{C}$ .

Question 11

A student is planning to test: Which material insulates best—foam, plastic, or fiberglass?

They will measure temperature every 30 minutes for 2 hours. Which data table setup best matches the plan and helps compare results?

A table with columns: Material | Color | Texture | Student opinion
A table with columns: Time (min) | Foam temp ( $^\circ\text{C}$ ) | Plastic temp ( $^\circ\text{C}$ ) | Fiberglass temp ( $^\circ\text{C}$ ), with rows for 0, 30, 60, 90, 120 minutes (correct answer)
A table with columns: Time (hours) | Best material so far, with only one row at the end of 2 hours
A table with columns: Starting temp | Ending temp, but no place to record which material was used

Question 12

A student is organizing steps for this investigation: How does mass of water affect the time to heat from 20°C to 80°C? They will test 100 g, 200 g, and 400 g of water using the same hot plate.

Which sequence of steps is the best order to conduct the investigation?

Heat water to 80°C first, then measure the mass, then decide what starting temperature was.
Measure masses of water (100 g, 200 g, 400 g) into identical containers, measure and record starting temperature (20°C), heat each on the same hot plate setting, start the timer when heating begins, stop timing when the water reaches 80°C, record time, and repeat trials to find an average. (correct answer)
Choose one mass of water, heat it several times, and use that time as the answer for all masses.
Heat all three masses on different burners so they finish faster, then compare times.

Question 13

A student wants to investigate the question: Which material insulates best—foam, plastic, or fiberglass? The student has 3 identical cups, a thermometer, hot water, and a timer. Which procedure is the best plan for a fair test of insulation?

Be sure the plan identifies what to change, what to measure, and what to keep the same.

Wrap each cup with a different material (foam, plastic, fiberglass), fill each with the same volume of water at the same starting temperature, cover the cups, place them side-by-side in the same room, measure and record the temperature of each cup every 30 minutes for 2 hours, repeat the test, and compare which cup stays warmest. (correct answer)
Fill each cup with a different volume of hot water, wrap each cup with a different material, and measure the temperature only at the end of 2 hours to see which is highest.
Wrap one cup with foam and place it in the freezer, wrap one cup with plastic and leave it on a counter, and wrap one cup with fiberglass and place it near a heater; then measure temperatures after 2 hours.
Wrap each cup with a different material, but start with different starting temperatures (one at 60°C, one at 70°C, one at 80°C) and measure every 30 minutes for 2 hours.

Question 14

A class is planning to test: Which material absorbs heat faster—metal, plastic, or wood? They have equal-mass samples of each material, an oven, thermometers, and a timer.

Which procedure best investigates heat absorption (heating) rather than cooling?

Heat all samples together in the oven for the same amount of time, then immediately measure each sample's temperature and compare which one increased the most from the same starting temperature. (correct answer)
Put the samples in the freezer overnight, then measure how cold they are the next morning.
Heat the metal sample in the oven, leave the plastic at room temperature, and soak the wood in water; then compare their temperatures.
Heat each sample to a different starting temperature, then place them on the same table and compare which one cools the slowest.

Question 15

A student is planning a heating investigation: How does mass affect heating time? They will test 100 g, 200 g, and 400 g of water, heating each from 20°C to 80°C.

Which materials/equipment list is most necessary to carry out this investigation safely and accurately?

Thermometer, stopwatch/timer, balance (scale), identical heat-safe containers, hot plate (or burner), water, safety goggles/heat gloves. (correct answer)
Ruler, magnets, protractor, plastic wrap, and a calculator.
Only a hot plate and three containers; time and temperature can be guessed.
Thermometer and ice cubes; no timer is needed because the temperature will change at the same rate for all masses.

Question 16

A student will test cooling in three identical insulated containers with the same volume of water, starting at 60°C, 70°C, and 80°C. The room stays at 20°C.

Which data table format is best for recording results so the cooling rates can be compared?

A table with columns: Container color | Student name | Best guess of cooling rate.
A table with columns: Time (min) | Temp at 60°C start (°C) | Temp at 70°C start (°C) | Temp at 80°C start (°C), with rows for 0, 5, 10, 15, 20, 25, 30 minutes. (correct answer)
A table with one row: Final temperature after 30 minutes for each container (no times listed).
A table with columns: Time (min) | Room temperature (°C) only.

Question 17

A student investigates: Which material insulates best—foam, plastic, or fiberglass? The student wraps three identical jars and fills each with 250 mL of water at $80\,^{\circ}\mathrm{C}$ . After 2 hours, the foam jar is $65\,^{\circ}\mathrm{C}$ , the plastic jar is $58\,^{\circ}\mathrm{C}$ , and the fiberglass jar is $67\,^{\circ}\mathrm{C}$ . Which conclusion is most supported by these results (assuming a fair test)?

Plastic is the best insulator because it had the lowest final temperature.
Fiberglass is the best insulator because it kept the water warmest (highest final temperature) after 2 hours. (correct answer)
All three materials insulated equally well because they started at the same temperature.
Foam must be the best insulator because it is thicker than the others (even though thickness was not measured).

Explanation: This question tests understanding of how to plan a complete temperature investigation by designing a procedure with proper variable control, selecting appropriate materials and equipment, and planning systematic measurements. Planning an investigation requires: (1) clarifying the research question (identifying what you want to find out: "Which material insulates best?" or "How does thickness affect cooling?"), which determines your variables (independent = what you'll change, dependent = what you'll measure); (2) designing procedure (step-by-step instructions ensuring fair test: prepare trials with independent variable values, set controlled variables constant, measure dependent variable systematically); (3) selecting materials and equipment (thermometers for temperature, timer for time intervals, appropriate containers and insulation materials, heat source if needed); (4) planning measurements (when to measure: intervals like every 30 min, or at specific times like 1 hr and 2 hr; what to measure: temperature in °C, time in minutes; how many: at least 3-5 measurements to show pattern); and (5) organizing data collection (prepare data table with columns for time/independent variable and rows for measurements, ready to record during investigation). For analyzing insulation results: best insulator maintains highest temperature (loses least heat), compare final temperatures after same time period, temperature drop indicates heat loss through insulation—smaller drop means better insulation. Choice B is correct because fiberglass kept water warmest (67°C) after 2 hours, indicating best insulation performance: fiberglass only dropped 13°C (80°C to 67°C), foam dropped 15°C (80°C to 65°C), plastic dropped 22°C (80°C to 58°C), therefore fiberglass lost least heat and insulated best. Choice A incorrectly states plastic is best because it had lowest final temperature (58°C)—this is backwards: lowest temperature means MOST heat lost, making plastic the WORST insulator, not best. Choice C incorrectly concludes all insulated equally because they started at same temperature—starting temperature was controlled variable (must be same for fair test), but different final temperatures clearly show different insulation effectiveness. Choice D makes assumption about foam thickness without measurement data—cannot conclude based on unmeasured variable, must base conclusion only on measured results (temperature), speculation about thickness is inappropriate without data. Data analysis for insulation comparison: (1) CALCULATE temperature drop: foam 80°C→65°C = 15°C drop, plastic 80°C→58°C = 22°C drop, fiberglass 80°C→67°C = 13°C drop; (2) RANK performance: smallest drop = best insulator, fiberglass (13°C) > foam (15°C) > plastic (22°C); (3) ALTERNATIVE analysis: cooling rate = ΔT/time, foam = 15°C/120min = 0.125°C/min, plastic = 22°C/120min = 0.183°C/min, fiberglass = 13°C/120min = 0.108°C/min, lowest rate = best insulator; (4) VERIFY conclusion: fiberglass best by both methods (highest final temp, lowest cooling rate), consistent with good insulation properties; (5) CONSIDER sources of error: measurement uncertainty (±1°C), slight differences in wrapping, ambient temperature fluctuations—but 9°C difference between best and worst is significant, conclusion reliable that fiberglass insulates best under these conditions.

Question 18

A student plans to investigate: How does the mass of water affect the time to heat from $20\,^{\circ}\mathrm{C}$ to $80\,^{\circ}\mathrm{C}$ ? Which sequence of steps is most appropriate?

Heat water to boiling, pour different amounts into different containers, and stop timing when bubbles appear.
Choose three different hot plates, heat 100 g, 200 g, and 400 g of water, and record the time whenever the student thinks it feels hot enough.
Measure out 100 g, 200 g, and 400 g of water into identical containers. Make sure each starts at $20\,^{\circ}\mathrm{C}$ . Heat each sample using the same hot plate setting, start the timer when heating begins, measure temperature until it reaches $80\,^{\circ}\mathrm{C}$ , record the time, and repeat trials to find an average time for each mass. (correct answer)
Put 100 g, 200 g, and 400 g of water in the same container at the same time and time how long it takes the combined water to reach $80\,^{\circ}\mathrm{C}$ .

Explanation: This question tests understanding of how to plan a complete temperature investigation by designing a procedure with proper variable control, selecting appropriate materials and equipment, and planning systematic measurements. Planning an investigation requires: (1) clarifying the research question (identifying what you want to find out: "Which material insulates best?" or "How does thickness affect cooling?"), which determines your variables (independent = what you'll change, dependent = what you'll measure); (2) designing procedure (step-by-step instructions ensuring fair test: prepare trials with independent variable values, set controlled variables constant, measure dependent variable systematically); (3) selecting materials and equipment (thermometers for temperature, timer for time intervals, appropriate containers and insulation materials, heat source if needed); (4) planning measurements (when to measure: intervals like every 30 min, or at specific times like 1 hr and 2 hr; what to measure: temperature in °C, time in minutes; how many: at least 3-5 measurements to show pattern); and (5) organizing data collection (prepare data table with columns for time/independent variable and rows for measurements, ready to record during investigation). For heating time vs mass investigation: proper sequence requires measuring masses precisely, verifying starting temperatures, using consistent heating method, timing accurately, and repeating for reliability—systematic approach ensures valid results. Choice C is correct because it includes all essential procedure steps in logical order: measure precise masses (100 g, 200 g, 400 g), verify starting temperature (all at 20°C), use same hot plate setting (controlled variable), start timer when heating begins (accurate timing), monitor temperature until reaches 80°C (clear endpoint), record time for each mass, and repeat trials for reliability (average reduces error). Choice A heats to boiling instead of 80°C (wrong target temperature), uses different amounts in different containers (uncontrolled container variable), stops timing "when bubbles appear" (vague, subjective endpoint—boiling point varies with altitude/pressure). Choice B uses three different hot plates (uncontrolled heat source—different plates may heat differently), relies on subjective "feels hot enough" (not objective 80°C measurement), lacks systematic approach. Choice D puts all masses in same container simultaneously (cannot determine individual heating times), measures combined water (defeats purpose of testing how mass affects heating time), violates basic experimental design. Complete procedure sequence: (1) SETUP: gather materials (balance, thermometer, timer, identical containers, hot plate), prepare data table; (2) MEASURE: weigh 100 g water in container 1 (use balance), verify temperature is 20°C (use thermometer); (3) HEAT: place on hot plate center, turn to medium setting (record setting number), start timer immediately; (4) MONITOR: check temperature every 30 seconds (watch for approach to 80°C), stir gently for even heating; (5) RECORD: when reaches 80°C, stop timer and record time; (6) REPEAT: let hot plate cool, repeat with 200 g (same procedure), then 400 g; (7) REPLICATE: do 2-3 trials of each mass, calculate average times; (8) ANALYZE: compare times (expect proportional to mass)—this systematic approach isolates mass effect on heating time.

Question 19

A student wants to investigate the question: Which material insulates best—foam, plastic, or fiberglass? The student has 3 identical cups, the 3 insulation materials, hot water, thermometers, and a timer. Which procedure would be the best fair test to answer the question?

Wrap three different-sized cups with foam, plastic, and fiberglass. Fill each cup with a different amount of hot water. Measure the temperature only at the end of 2 hours and decide which worked best.
Use one cup. Wrap it with foam, fill with hot water, and measure temperature every 30 minutes for 2 hours. Repeat with plastic and fiberglass on different days without checking the room temperature.
Prepare 3 identical cups and label them foam, plastic, and fiberglass. Wrap each cup with the assigned insulation (same thickness if possible). Pour the same volume of water at the same starting temperature into each cup, cover them, place them side-by-side in the same room, and record the temperature of each cup at regular intervals (for example, every 30 minutes for 2 hours). Compare the temperature drop to determine the best insulator. (correct answer)
Wrap one cup with each material and place the cups in different locations (sunny window, shade, near a vent). Add hot water and record the temperature whenever you remember. The cup that stays warmest is the best insulator.

Explanation: This question tests understanding of how to plan a complete temperature investigation by designing a procedure with proper variable control, selecting appropriate materials and equipment, and planning systematic measurements. Planning an investigation requires: (1) clarifying the research question (identifying what you want to find out: "Which material insulates best?" or "How does thickness affect cooling?"), which determines your variables (independent = what you'll change, dependent = what you'll measure); (2) designing procedure (step-by-step instructions ensuring fair test: prepare trials with independent variable values, set controlled variables constant, measure dependent variable systematically); (3) selecting materials and equipment (thermometers for temperature, timer for time intervals, appropriate containers and insulation materials, heat source if needed); (4) planning measurements (when to measure: intervals like every 30 min, or at specific times like 1 hr and 2 hr; what to measure: temperature in °C, time in minutes; how many: at least 3-5 measurements to show pattern); and (5) organizing data collection (prepare data table with columns for time/independent variable and rows for measurements, ready to record during investigation). For insulation comparison investigation: Planning to answer "Which insulation material keeps water hot longest?" requires: (1) SETUP: obtain three identical containers (same size, shape, material—plastic cups for example), obtain insulation materials (foam sheet, plastic sheet, fiberglass—enough to wrap each container with same thickness), wrap each container with different material (Container A: foam, Container B: plastic, Container C: fiberglass, all wrapped to 2 cm thickness for consistency), label containers clearly; (2) PREPARATION: heat water to 80°C (use kettle or hot plate, verify with thermometer), pour exactly 500 mL into each container (measured with graduated cylinder or measuring cup—same volume all trials), seal containers with identical lids (prevent evaporation and convection), record starting temperature (all should be 80°C, verify); (3) MEASUREMENT: place all three containers in same room (same ambient temperature ~20°C, fair comparison), measure temperature every 30 minutes for 2 hours (intervals: 0, 30, 60, 90, 120 min), use same thermometer or three identical calibrated thermometers (measurement consistency), record in data table (time | foam temp | plastic temp | fiberglass temp); (4) CONTROL: controlled variables include water volume (500 mL all), starting temperature (80°C all), insulation thickness (2 cm all), container size (identical), ambient temperature (same room simultaneously), lid type (same seal all)—these must be constant for fair test isolating material effect; and (5) ANALYSIS: compare final temperatures (at 120 min: which highest? that material insulated best), or compare cooling rates (which cooled slowest?), conclude which material most effective. Choice C is correct because it includes all essential procedure steps (setup, measurement, variable control, data recording), correctly identifies necessary materials and equipment, properly plans measurements at appropriate intervals and duration, and appropriately ensures fair test by controlling variables systematically. Choice A violates fair test: allows controlled variables to vary (different-sized cups, different amounts of water) making comparison invalid, and measures only at end (missing intermediate data showing cooling pattern). Choice B doesn't test simultaneously (different days means different room conditions), doesn't check room temperature (uncontrolled variable), and tests one at a time (not fair comparison). Choice D places cups in different locations (sunny window, shade, near vent—different ambient conditions), measures "whenever you remember" (inconsistent timing), violating fair test principles. Complete investigation planning ensures reliable results: identical containers wrapped with same thickness of each material, same water volume and starting temperature, simultaneous testing in same environment, regular measurement intervals, proper data recording—this systematic approach isolates the effect of insulation material type while controlling all other factors that could affect cooling rate.

Question 20

Investigation question: How does the mass of water affect the time it takes to heat from $20^\circ\text{C}$ to $80^\circ\text{C}$ ?

A student plans to test 100 g, 200 g, and 400 g of water using the same hot plate. Which set of variables is identified correctly?

Choose the option that correctly matches independent, dependent, and controlled variables.

Independent: time to reach $80^\circ\text{C}$ ; Dependent: mass of water; Controlled: starting temperature only
Independent: hot plate setting; Dependent: container type; Controlled: mass of water
Independent: mass of water; Dependent: time to reach $80^\circ\text{C}$ ; Controlled: starting temperature, hot plate setting, container type, and stirring method (correct answer)
Independent: room temperature; Dependent: mass of water; Controlled: target temperature