5th Grade Science Quiz: Measure Weight Before And After
20 questions · exam conditions
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Measure Weight Before And AfterQuestion 1 of 20

Chen sealed 50 g ice in a bag, melted it; how did weight after compare?

The weight stayed 50 g because the sealed bag kept all matter inside.
The weight decreased because ice weighs less after it melts.
The weight increased because water weighs more than ice.
The weight changed because melting always changes total weight.
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5th Grade Science Quiz

5th Grade Science Quiz: Measure Weight Before And After

Practice Measure Weight Before And After in 5th Grade 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 Measure Weight Before And After, giving you a quick way to practice the rules, question types, and explanations that matter most for 5th Grade 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

Chen sealed 50 g ice in a bag, melted it; how did weight after compare?

  1. The weight stayed 50 g because the sealed bag kept all matter inside. (correct answer)
  2. The weight decreased because ice weighs less after it melts.
  3. The weight increased because water weighs more than ice.
  4. The weight changed because melting always changes total weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—it just changes form or arrangement; for example, when ice melts to water, the particles go from an organized solid to a liquid that can flow, but the same number of particles are still there, so the weight stays at 50 grams, and measuring before and after provides evidence that matter is conserved. Choice A is correct because it accurately states that the weight stayed 50 g because the sealed bag kept all matter inside, demonstrating understanding that melting does not create or destroy matter, only changes its form, so the weight measured before equals the weight measured after. Choice B represents the misconception that the weight decreased because ice weighs less after it melts; this error occurs because students focus on observable changes like the state from solid to liquid and incorrectly assume these changes affect weight, or they think liquids are lighter without understanding particle conservation. To help students, conduct hands-on weighing activities where they predict, measure before melting, observe the change, measure after, and compare using sealed bags to ensure nothing escapes; create data tables with 'Before' and 'After' columns, emphasize the scale measures total matter present, watch for beliefs that melting changes weight, and always ask 'Did any new matter come in? If not, weight must stay the same.'

Question 2

Chen dissolved 10 g sugar into 100 g water; total was 110 g before and after. What happened?

  1. The weight decreased because the sugar disappeared in the water.
  2. The weight increased because mixing creates extra matter.
  3. The weight stayed the same at 110 g because all matter was still there. (correct answer)
  4. The weight changed because dissolved sugar has no weight anymore.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes (melting, freezing, dissolving, mixing) and chemical changes (when measured in closed systems) because matter is not created or destroyed—it just changes form or arrangement. When sugar dissolves in water, sugar particles spread between water particles (both still present), so 10g sugar + 100g water = 110g solution. Choice C is correct because it accurately states that the total weight stayed the same at 110 g because all matter was still there, demonstrating understanding that dissolving does not create or destroy matter, only changes its form or arrangement, so the weight measured before equals the weight measured after. Choice A represents the misconception that dissolved substances disappear and lose weight; this error occurs because students think dissolved substances disappear rather than recognizing particles are still present but too small to see. To help students: Conduct hands-on weighing activities where students predict, measure before, observe the change, measure after, and compare. Use closed systems (sealed bags, sealed bottles) when possible to ensure nothing escapes. Create data tables with 'Before' and 'After' columns to make comparison clear. Emphasize: the number on the scale measures the total amount of matter present—if all the matter stays in the system, the number stays the same. Watch for: Students who think dissolving makes substances disappear. Always ask: 'Did any matter leave the system? Did any new matter come in? If not, weight must stay the same.'

Question 3

In this experiment, Amir mixed 25 g salt and 25 g sand; after mixing, what happened to total weight?

  1. The weight increased because mixing created new matter.
  2. The weight stayed 50 g because both materials were still there. (correct answer)
  3. The weight decreased because some salt disappeared in the sand.
  4. The weight changed because the mixture looked different.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like mixing because matter is not created or destroyed—particles just get rearranged. When 25g salt mixes with 25g sand, salt and sand particles intermingle but all particles remain present, so the weight stays at 50 grams total. Choice B is correct because it accurately states that the total weight stayed the same (remained constant at 50 g) and correctly identifies that both materials were still there after mixing. This demonstrates understanding that mixing does not create or destroy matter, only rearranges salt and sand particles together, so the weight measured before equals the weight measured after. Choice C represents the misconception that some salt disappeared in the sand during mixing. This error occurs because students might think that when two substances mix and one seems less visible, some of it has vanished, not understanding that all the original particles are still present just distributed differently. To help students: Conduct hands-on weighing activities where students measure 25g salt and 25g sand separately, record weights, mix them in a clear container, then weigh the mixture. Use different colored materials when possible to show both are still visible. Create data tables showing salt weight + sand weight = mixture weight. Emphasize: mixing just moves particles around—every grain of salt and sand that went in is still there. Watch for: Students who think mixing makes matter disappear or who believe the mixture should weigh differently than the sum of its parts.

Question 4

In this experiment, Chen put 10 g baking soda and 50 g vinegar into a 100 g bottle and sealed it; total was 160 g. After the reaction, it was still 160 g. What do these measurements show about matter during the reaction?

  1. The weight decreased because the gas escaped through the sealed cap.
  2. The weight stayed 160 g because all products stayed inside the bottle. (correct answer)
  3. The weight increased because the bubbles made new matter.
  4. The weight changed because reactions always destroy some matter.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter during chemical changes. The total weight of matter stays the same during chemical changes when measured in closed systems because atoms rearrange but are not created or destroyed. When baking soda and vinegar react in a sealed bottle, they produce carbon dioxide gas, water, and dissolved salts—all products remain trapped inside, so the total weight stays 160 grams. Choice B is correct because it accurately states that the weight stayed 160 g and correctly explains that all products stayed inside the bottle due to the seal. This demonstrates understanding that chemical reactions rearrange matter into new substances but conserve total mass when nothing escapes, so the weight measured before equals the weight measured after. Choice D represents the misconception that chemical reactions always destroy some matter, which occurs because students see dramatic changes like fizzing and bubbling and assume matter is being destroyed, not understanding that atoms simply rearrange into new combinations with the same total mass. To help students: Conduct this reaction in both sealed and open containers to compare results—sealed stays 160g while open loses weight as gas escapes. Have students predict, measure all components before mixing, observe the reaction, then measure after. Create data tables comparing sealed vs. open results. Emphasize: reactions rearrange atoms like rearranging building blocks—you can build different things but still have the same number of blocks. Watch for students who think reactions destroy matter or that dramatic changes must mean weight changes.

Question 5

In this experiment, Sofia weighed 25 g salt and 25 g sand for 50 g total. After mixing, the bowl still weighed 50 g. Which statement best describes what happened to the total weight?

  1. The weight increased because mixing created extra matter in the bowl.
  2. The weight decreased because some sand turned into dust and floated away.
  3. The weight stayed 50 g because the same matter was present. (correct answer)
  4. The weight changed because the salt and sand cannot keep the same weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like mixing because matter is not created or destroyed—it just changes arrangement. When salt and sand are mixed together, the particles intermingle but every grain remains present, so 25g salt + 25g sand = 50g mixture. Choice C is correct because it accurately states that the total weight stayed 50 g and correctly explains that the same matter was present before and after mixing. This demonstrates understanding that mixing only rearranges particles without creating or destroying them, so the weight measured before equals the weight measured after. Choice B represents the misconception that some matter can turn to dust and float away during mixing, which occurs because students may see fine particles in the air and think matter is being lost, not understanding that any visible dust would need to leave the bowl to change the weight, and the problem states the bowl still weighed 50g. To help students: Conduct hands-on weighing activities where students measure salt and sand separately in small cups, pour both into a mixing bowl, stir gently to avoid creating dust clouds, then measure the mixture. Use a deep bowl and mix slowly to keep all material inside. Create data tables showing 25g + 25g = 50g with clear labels. Emphasize: if the scale still shows 50g, then all the salt and sand must still be in the bowl—nothing escaped. Watch for students who think mixing can make matter disappear or that fine particles don't count toward total weight.

Question 6

Sofia left 50 g ice in a sealed bag until it melted; what do measurements show?

  1. The weight decreased because melting destroys some of the ice.
  2. The weight stayed the same at 50 g, showing matter stayed in the bag. (correct answer)
  3. The weight increased because liquid water weighs more than ice.
  4. The weight changed because any change of state changes total weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—water molecules simply change arrangement. When ice melts in a sealed bag, the organized crystal structure becomes freely moving liquid, but the same H₂O molecules are present, so weight remains 50 grams. Choice B is correct because it accurately states that the weight stayed the same at 50g and correctly notes this shows matter stayed in the bag. This demonstrates understanding that phase changes rearrange particles without creating or destroying them, confirming conservation of matter through measurement. Choice C represents the misconception that liquid water weighs more than ice. This error occurs because students may notice water seems denser or takes up less space than ice, incorrectly connecting density or volume changes with weight changes, rather than recognizing mass remains constant. To help students: Set up multiple sealed bags with different amounts of ice (25g, 50g, 75g), weigh each before melting, let melt completely at room temperature, then reweigh to show consistent results. Create graphs plotting "Ice Weight" vs "Water Weight" to show a perfect 1:1 relationship. Use food coloring in the ice to make the transformation more visible while emphasizing the dye doesn't affect weight. Watch for: Students who confuse density (ice floats) with weight, or who think the "wetness" of water adds weight.

Question 7

Jamal sealed 40 g of chocolate in a bag; after it melted, how did the total weight compare?

  1. The weight increased because melted chocolate weighs more.
  2. The weight decreased because some chocolate escaped the sealed bag.
  3. The weight stayed 40 g because all the chocolate stayed inside. (correct answer)
  4. The weight changed because solid and liquid weigh differently.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—it just changes form. When chocolate melts from solid to liquid, the particles go from tightly packed to flowing freely, but the same number of particles remain, so the weight stays at 40 grams. Choice C is correct because it accurately states that the total weight stayed the same (remained constant at 40 g) and correctly identifies that all the chocolate stayed inside the sealed bag. This demonstrates understanding that melting does not create or destroy matter, only changes how particles are arranged, so the weight measured before equals the weight measured after. Choice D represents the misconception that solid and liquid forms of the same substance weigh differently. This error occurs because students focus on the dramatic visual change from solid chocolate to liquid and incorrectly assume this must affect weight, not understanding that the same chocolate particles are present in both forms. To help students: Conduct hands-on weighing activities where students seal chocolate pieces in a plastic bag, weigh it, melt the chocolate in warm water, then weigh again. Use clear bags so students can see the state change. Create data tables comparing weights before and after melting. Emphasize: whether the chocolate is solid or liquid, it's still the same chocolate particles—just arranged differently. Watch for: Students who think different states of matter have different weights or who believe melting changes the amount of matter.

Question 8

In this experiment, Maya put 10 g baking soda and 50 g vinegar into a 100 g bottle and sealed it; total was 160 g. After fizzing stopped, it was 160 g. Why did the weight stay the same after fizzing?

  1. The weight stayed 160 g because the sealed bottle kept all matter inside. (correct answer)
  2. The weight decreased because the gas has no weight.
  3. The weight increased because bubbles add extra weight.
  4. The weight changed because a chemical reaction must change weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter during chemical changes. The total weight of matter stays the same during chemical changes when measured in closed systems because matter is not created or destroyed—it just rearranges into new substances. When baking soda and vinegar react, they produce carbon dioxide gas, water, and dissolved salts, but in a sealed bottle all products stay inside, so the total weight remains 160 grams. Choice A is correct because it accurately states that the total weight stayed 160 g and correctly explains that the sealed bottle kept all matter inside, including the gas produced. This demonstrates understanding that chemical reactions rearrange atoms but don't destroy them, so the weight measured before equals the weight measured after in a closed system. Choice B represents the misconception that gas has no weight, which occurs because students can't see gas and incorrectly assume invisible things don't weigh anything, not understanding that gas particles have mass and contribute to total weight. To help students: Conduct this exact experiment using a plastic bottle with tight cap, having students predict and measure before mixing, observe the fizzing reaction, then measure after. Emphasize sealing the bottle BEFORE adding vinegar to trap all gas. Create data tables showing bottle + baking soda + vinegar = 160g before and after. Point out that if they opened the bottle and gas escaped, the weight would decrease, proving gas has weight. Watch for students who think gases don't weigh anything or that chemical reactions must change total weight.

Question 9

In this experiment, Maya sealed 50 g of ice; after melting to water, what do the measurements show about matter?

  1. The weight decreased because melting destroys some matter.
  2. The weight stayed 50 g, showing matter stayed the same in the bag. (correct answer)
  3. The weight increased because water has more matter than ice.
  4. The weight changed because the ice looked different after melting.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—it just changes form or arrangement. When ice melts to water in a sealed bag, the organized solid structure becomes liquid that can flow, but the same number of water molecules remain, keeping the weight at 50 grams. Choice B is correct because it accurately states that the total weight stayed the same (remained constant at 50 g) and correctly explains this shows matter stayed the same in the bag. This demonstrates understanding that the measurements prove matter is conserved during melting—the same amount of matter exists before and after, just in different forms. Choice A represents the misconception that melting destroys some matter. This error occurs because students might think that when ice becomes water, some of it is lost in the process, not understanding that every water molecule in the ice is still present in the liquid water. To help students: Conduct hands-on weighing activities where students predict what will happen to weight, seal ice in a bag, weigh it, let it melt completely, then weigh again. Have students draw particle models showing ice structure versus water to visualize that the same particles are present. Create data tables and graphs showing weight stays constant. Emphasize: the scale proves that all the water molecules that were locked in ice are now moving freely as liquid—none were created or destroyed. Watch for: Students who think state changes destroy matter or who don't connect weight measurements to conservation of matter.

Question 10

In this experiment, Jamal weighed a cup of water at 200 g, froze it overnight, and weighed the cup of ice at 200 g. Which statement best describes what happened to the total weight?

  1. The weight increased because ice is heavier than liquid water.
  2. The weight changed because freezing always changes weight.
  3. The weight stayed 200 g because the same matter remained. (correct answer)
  4. The weight decreased because some water disappeared in the freezer.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like freezing because matter is not created or destroyed—it just changes form or arrangement. When water freezes to ice, the particles go from liquid that can flow to organized solid structure, but the same number of water molecules are still there, so the weight stays at 200 grams. Choice C is correct because it accurately states that the total weight stayed 200 g and correctly explains that the same matter remained in the cup. This demonstrates understanding that freezing does not create or destroy matter, only changes its form from liquid to solid, so the weight measured before equals the weight measured after. Choice A represents the misconception that ice is heavier than liquid water, which occurs because students focus on ice feeling more solid and incorrectly assume solid things weigh more than liquids, not understanding that the same water molecules are present in both states. To help students: Conduct hands-on weighing activities where students predict, measure water in a cup, freeze overnight, then measure the ice in the same cup. Create data tables with 'Before Freezing' and 'After Freezing' columns to make the 200g = 200g comparison clear. Emphasize: the number on the scale measures the total amount of matter present—if all the water stays in the cup, the number stays the same whether it's liquid or ice. Watch for students who think freezing changes weight or that ice and water have different weights.

Question 11

After Amir mixed 25 g salt with 25 g sand in a bowl, which statement best describes total weight?

  1. The weight stayed 50 g because no matter was added or removed. (correct answer)
  2. The weight decreased because mixing makes some matter disappear.
  3. The weight increased because mixing creates new matter.
  4. The weight changed because the two materials touched each other.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like mixing because matter is not created or destroyed—particles just intermingle. When 25g salt combines with 25g sand, the particles mix together but every grain of each remains present, maintaining the total weight at 50 grams. Choice A is correct because it accurately states that the total weight stayed the same (remained constant at 50 g) and correctly identifies that no matter was added or removed during mixing. This demonstrates understanding that mixing only rearranges particles without creating or destroying them, so the weight measured before equals the weight measured after. Choice B represents the misconception that mixing makes some matter disappear. This error occurs because students might think that when substances combine, especially if one becomes less visible among the other, some of it vanishes, not understanding that mixing is just rearrangement. To help students: Conduct hands-on weighing activities where students measure salt and sand separately on paper plates, record individual weights, pour both into one container, mix thoroughly, then weigh the mixture. Use magnifying glasses to show both substances are still visible in the mixture. Create addition equations showing 25g + 25g = 50g before and after. Emphasize: mixing is like shuffling two decks of cards together—you still have all the same cards, just mixed up. Watch for: Students who think mixing causes matter to disappear or who don't understand that total weight equals the sum of parts.

Question 12

Maya melted 40 g chocolate in a sealed bag; how did weight after melting compare?

  1. The weight changed because solid chocolate weighs more than melted chocolate.
  2. The weight decreased because some chocolate escaped as it melted.
  3. The weight stayed the same at 40 g before and after melting. (correct answer)
  4. The weight increased because melting creates more chocolate in the bag.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—particles just move more freely. When chocolate melts, the cocoa butter and other particles go from solid to liquid form but all particles remain, so the weight stays at 40 grams. Choice C is correct because it accurately states that the weight stayed the same at 40g before and after melting. This demonstrates understanding that melting does not create or destroy matter, only changes how particles are arranged and move, so the weight measured before equals the weight measured after. Choice A represents the misconception that solid chocolate weighs more than melted chocolate. This error occurs because students focus on the change from hard to soft/liquid and incorrectly assume this visible change means weight changes, rather than recognizing the same chocolate particles are present in both forms. To help students: Melt chocolate chips in sealed plastic bags using warm water baths, weighing before and after to show 40g solid = 40g melted. Let chocolate cool and re-solidify, then weigh again to show reversibility. Create three-column data tables: "Solid Weight," "Melted Weight," "Re-solidified Weight" all showing 40g. Emphasize: melting just lets particles slide around instead of staying locked in place—it's still the same chocolate! Watch for: Students who think state changes affect weight or that liquids weigh less than solids.

Question 13

Chen stirred 10 g sugar into 100 g water (110 g total); after dissolving, which is true?

  1. The weight stayed the same at 110 g because all the matter remained. (correct answer)
  2. The weight decreased because the sugar vanished when it dissolved.
  3. The weight increased because dissolving adds extra matter to the water.
  4. The weight changed because the sugar-water looks different after stirring.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like dissolving because matter is not created or destroyed—sugar particles just spread throughout water. When sugar dissolves, its particles fit between water particles but both substances remain present, so 10g sugar + 100g water = 110g solution. Choice A is correct because it accurately states that the weight stayed the same at 110g and correctly explains that all the matter remained. This demonstrates understanding that dissolving disperses particles but doesn't eliminate them, so total weight is conserved. Choice B represents the misconception that sugar vanished when it dissolved. This error occurs because students can no longer see the sugar once dissolved and incorrectly assume invisible means gone, rather than recognizing sugar particles are still present but too small and spread out to see. To help students: Dissolve sugar in warm water while students observe and weigh at each step: dry sugar (10g), water (100g), solution (110g). Evaporate some solution to show sugar reappears, proving it was there all along. Create visual models using marbles to show how sugar particles fit between water particles. Emphasize: "Can't see it" doesn't mean "not there"—the sweet taste proves sugar is still present! Always ask: "If we evaporated all the water, would we get our 10g of sugar back? Yes? Then it must still be in there!"

Question 14

In this experiment, Sofia melted 50 g ice in a sealed bag; how did weight change?

  1. The weight increased because melted water weighs more than ice.
  2. The weight stayed the same at 50 g because nothing could escape. (correct answer)
  3. The weight decreased because some water leaked out while melting.
  4. The weight changed because a solid turning to liquid changes weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes (melting, freezing, dissolving, mixing) and chemical changes (when measured in closed systems) because matter is not created or destroyed—it just changes form or arrangement. For example, when ice melts to water, the particles go from organized solid to liquid that can flow, but the same number of particles are still there, so the weight stays at 50 grams. Choice B is correct because it accurately states that the total weight stayed the same at 50 g because nothing could escape, demonstrating understanding that melting does not create or destroy matter, only changes its form or arrangement, so the weight measured before equals the weight measured after. Choice A represents the misconception that weight changes when substances change form, such as thinking melted water weighs more than ice; this error occurs because students focus on observable changes like appearance or state and incorrectly assume these changes affect weight. To help students: Conduct hands-on weighing activities where students predict, measure before, observe the change, measure after, and compare. Use closed systems (sealed bags, sealed bottles) when possible to ensure nothing escapes. Create data tables with 'Before' and 'After' columns to make comparison clear. Emphasize: the number on the scale measures the total amount of matter present—if all the matter stays in the system, the number stays the same. Watch for: Students who think melting/freezing changes weight, or who believe heating makes things weigh less. Always ask: 'Did any matter leave the system? Did any new matter come in? If not, weight must stay the same.'

Question 15

A cup weighed 200 g before water froze; after freezing it weighed 200 g. How do the weights compare?

  1. The weight stayed 200 g because freezing did not remove any matter. (correct answer)
  2. The weight increased because ice weighs more than liquid water.
  3. The weight decreased because the cold made the water weigh less.
  4. The weight changed because turning to ice changes total weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like freezing because matter is not created or destroyed—it just changes form; for example, when water freezes in a cup, it becomes ice but the same amount of matter is there, so the weight stays at 200 grams, and measuring before and after confirms conservation. Choice A is correct because it accurately states that the weight stayed 200 g because freezing did not remove any matter, demonstrating understanding that freezing does not create or destroy matter, only changes its form, so the weight measured before equals the weight measured after. Choice B represents the misconception that the weight increased because ice weighs more than liquid water; this error occurs because students might confuse volume expansion with weight gain, not understanding that appearance changes don't affect total matter. To help students, conduct hands-on weighing activities with cups where they predict, measure before freezing, observe the change, measure after, and compare; use data tables with 'Before' and 'After' columns, emphasize temperature changes don't alter amount, watch for state change weight myths, and ask 'Did any matter enter or leave? If not, weight must stay the same.'

Question 16

Emma froze a cup of water weighing 200 g; after freezing, how did weight compare?

  1. The weight decreased because ice is lighter than the same water.
  2. The weight stayed the same at 200 g before and after freezing. (correct answer)
  3. The weight increased because freezing adds extra matter to the cup.
  4. The weight changed because temperature changes always change weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like freezing because matter is not created or destroyed—water molecules just arrange differently. When water freezes to ice, the particles go from freely moving liquid to organized solid crystal structure, but the same number of particles are still there, so the weight stays at 200 grams. Choice B is correct because it accurately states that the weight stayed the same at 200g before and after freezing. This demonstrates understanding that freezing does not create or destroy matter, only changes how water molecules are arranged, so the weight measured before equals the weight measured after. Choice A represents the misconception that ice is lighter than water. This error occurs because students confuse the fact that ice floats (due to lower density from expanded crystal structure) with having less weight, not recognizing that the same amount of matter is present. To help students: Conduct hands-on weighing activities where students measure water in a container, mark the water level, freeze it completely, then weigh the ice to show 200g water = 200g ice. Use clear containers to observe volume changes while emphasizing weight stays constant. Create data tables comparing "Weight Before Freezing" and "Weight After Freezing" to make the pattern clear. Watch for: Students who think ice weighs less because it floats, or who confuse volume changes with weight changes.

Question 17

Marcus melted a 40 g chocolate bar in a sealed bag; how did total weight compare after melting?

  1. The weight stayed 40 g because the sealed bag kept all matter inside. (correct answer)
  2. The weight increased because liquid chocolate weighs more than solid chocolate.
  3. The weight decreased because some chocolate escaped during melting.
  4. The weight changed because melting always changes total weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like melting because matter is not created or destroyed—solid chocolate particles gain energy and flow as liquid, but the same number of particles remain, so 40g solid chocolate becomes 40g melted chocolate. Choice A is correct because it accurately states that the weight stayed 40g and explains that the sealed bag kept all matter inside, demonstrating understanding that melting only changes how particles are arranged. Choice B represents the misconception that liquid chocolate weighs more than solid chocolate, which occurs because students see the chocolate spread out and look different, incorrectly assuming this visual change means a weight change. To help students: Use sealed plastic bags with chocolate pieces on scales, warming gently to melt while monitoring weight. Create before/after comparison charts showing weight stays constant despite dramatic appearance change. Ask students why using a sealed bag is important (prevents any chocolate from escaping) to reinforce that weight only changes if matter enters or leaves.

Question 18

Keisha heated 150 g water in a sealed container; how did the weight after heating compare?

  1. The weight increased because hot water weighs more than cold water.
  2. The weight decreased because heating makes water lose weight.
  3. The weight changed because temperature changes always change weight.
  4. The weight stayed 150 g because nothing could escape the container. (correct answer)
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during changes like heating because matter is not created or destroyed—it just changes particle movement; for example, when water is heated in a sealed container, particles move faster but the amount remains the same, so the weight stays at 150 grams, and measuring before and after shows conservation. Choice D is correct because it accurately states that the weight stayed 150 g because nothing could escape the container, demonstrating understanding that heating does not create or destroy matter, only changes its temperature and particle speed, so the weight measured before equals the weight measured after. Choice B represents the misconception that the weight decreased because heating makes water lose weight; this error occurs because students might think heat causes evaporation or loss, not accounting for the sealed system preventing escape. To help students, conduct hands-on weighing activities with sealed containers where they predict, measure before heating, observe the change, measure after, and compare; use data tables with 'Before' and 'After' columns, emphasize that in closed systems nothing leaves, watch for ideas that temperature affects weight, and always ask 'Did any matter enter or leave? If not, weight must stay the same.'

Question 19

Keisha measured 10 g sugar + 100 g water = 110 g; after dissolving, what happened to total weight?

  1. The weight increased because the sugar turned into more liquid.
  2. The weight changed because dissolved sugar cannot be measured.
  3. The weight stayed 110 g because all the matter was still there. (correct answer)
  4. The weight decreased because the sugar disappeared in the water.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like dissolving because matter is not created or destroyed—particles just spread out. When 10g sugar dissolves in 100g water, sugar particles distribute between water particles, but all particles remain, keeping the total at 110 grams. Choice C is correct because it accurately states that the total weight stayed the same (remained constant at 110 g) and correctly identifies that all the matter was still there after dissolving. This demonstrates understanding that dissolving disperses sugar particles throughout water without destroying them, so the weight measured before equals the weight measured after. Choice D represents the misconception that sugar disappeared in the water and lost weight. This error occurs because students see the sugar vanish visually and conclude it's gone, not understanding that dissolved particles are still present but too small and spread out to see. To help students: Conduct hands-on weighing activities where students measure sugar and water separately, calculate the sum, mix and stir until dissolved, then weigh the solution. Use warm water to speed dissolving and have students taste the sweet solution as evidence sugar is still there. Create visual models showing sugar particles between water particles. Emphasize: just because we can't see the sugar doesn't mean it's gone—it's hiding between water particles, and the scale proves every bit is still there. Watch for: Students who think clear solutions mean the solute vanished or who believe dissolving destroys matter.

Question 20

Sofia heated 150 g of water in a sealed container; after heating (not boiling), how did total weight compare?

  1. The weight decreased because hot water weighs less than cold water.
  2. The weight increased because heating adds weight to water.
  3. The weight stayed 150 g because nothing could escape the container. (correct answer)
  4. The weight changed because temperature changes always change weight.
Explanation: This question tests understanding that weight can be measured before and after changes, and that total weight is conserved when heating, cooling, or mixing substances (NGSS 5-PS1-2). Students must interpret measurement data to recognize conservation of matter. The total weight of matter stays the same during physical changes like heating (without boiling) because matter is not created or destroyed—particles just move faster. When water is heated in a sealed container, water molecules gain energy and move more quickly, but the same number of molecules remain, so the weight stays at 150 grams. Choice C is correct because it accurately states that the total weight stayed the same (remained constant at 150 g) and correctly identifies that nothing could escape the sealed container. This demonstrates understanding that heating without boiling does not create or destroy matter, only increases particle movement, so the weight measured before equals the weight measured after. Choice A represents the misconception that hot water weighs less than cold water. This error occurs because students might associate heat with things rising (like hot air) and incorrectly assume hot substances weigh less, not understanding that temperature affects particle speed but not the amount of matter. To help students: Conduct hands-on weighing activities where students measure cold water in a sealed container, heat it carefully (not to boiling), then measure again. Use clear sealed containers so students can observe any changes. Create data tables with 'Before Heating' and 'After Heating' columns. Emphasize: heating makes water molecules dance faster but doesn't make any disappear—the scale still counts all the same molecules. Watch for: Students who think temperature changes weight or who confuse heating with evaporation.