CAEC Science Preparation Course: Inquiry: questions, hypotheses and variables

1. Pergunta 1 de 16

   In an experiment, what is the independent variable?

   • AThe group of subjects that gets no treatment at all
   • BThe factor that is measured as the result of the test
   • CThe factor the scientist changes on purpose
   • DA factor that is kept exactly the same in every trial
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   Resposta: C. The factor the scientist changes on purpose

   The independent (manipulated) variable is the one the scientist chooses and changes.

2. Pergunta 2 de 16

   In an experiment, what is the dependent variable?

   • AThe person who plans and runs the experiment
   • BAny factor that is kept the same in every trial
   • CThe factor the scientist changes on purpose
   • DThe factor measured to see the effect
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   Resposta: D. The factor measured to see the effect

   The dependent (responding) variable is what you measure. It may depend on the change you made.

3. Pergunta 3 de 16

   Why do scientists keep controlled variables the same in a fair test?

   • ASo the results will always match what the hypothesis predicted
   • BSo only the independent variable can explain the results
   • CSo there is no need to measure or record anything at all
   • DSo the experiment takes less time and uses less equipment
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   Resposta: B. So only the independent variable can explain the results

   If only one factor changes, you can tell what caused the result.

4. Pergunta 4 de 16

   What is the independent variable in Maya's experiment?

   Maya wants to know if the amount of salt in water changes how fast an ice cube melts. She fills four identical cups with 200 mL of tap water at room temperature. She adds 0 g, 5 g, 10 g and 15 g of salt, drops one ice cube of the same size into each cup and times how long each cube takes to melt.

   • AThe amount of salt in the water
   • BThe time it takes the ice to melt
   • CThe size of the cups
   • DThe volume of water
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   Resposta: A. The amount of salt in the water

   Maya chooses and changes the amount of salt: 0, 5, 10 and 15 g.

5. Pergunta 5 de 16

   What is the dependent variable in Maya's experiment?

   Maya wants to know if the amount of salt in water changes how fast an ice cube melts. She fills four identical cups with 200 mL of tap water at room temperature. She adds 0 g, 5 g, 10 g and 15 g of salt, drops one ice cube of the same size into each cup and times how long each cube takes to melt.

   • AThe temperature of the room during the test
   • BThe amount of salt added to each cup
   • CThe number of identical cups that Maya used
   • DThe time each ice cube takes to melt
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   Resposta: D. The time each ice cube takes to melt

   Maya measures melting time to see if it depends on the salt.

6. Pergunta 6 de 16

   Which cup acts as the control in Maya's experiment?

   Maya wants to know if the amount of salt in water changes how fast an ice cube melts. She fills four identical cups with 200 mL of tap water at room temperature. She adds 0 g, 5 g, 10 g and 15 g of salt, drops one ice cube of the same size into each cup and times how long each cube takes to melt.

   • AThe cup with 0 g of salt
   • BEvery cup with salt in it
   • CThe cup with 15 g of salt
   • DThe cup that melts fastest
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   Resposta: A. The cup with 0 g of salt

   The cup with no salt is the normal condition that the salted cups are compared with.

7. Pergunta 7 de 16

   Which is a controlled variable in Maya's experiment?

   Maya wants to know if the amount of salt in water changes how fast an ice cube melts. She fills four identical cups with 200 mL of tap water at room temperature. She adds 0 g, 5 g, 10 g and 15 g of salt, drops one ice cube of the same size into each cup and times how long each cube takes to melt.

   • AThe amount of salt in each cup
   • BThe volume of water
   • CWhether or not each ice cube melts
   • DThe time each ice cube takes to melt
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   Resposta: B. The volume of water

   Every cup has 200 mL of water, so volume is kept the same.

8. Pergunta 8 de 16

   Which group is the control group in Jordan's experiment?

   Jordan plants 40 bean seeds in identical pots with the same soil. He randomly puts 20 pots in Group A and 20 in Group B. Both groups get the same light and 100 mL of water every two days. Group B also gets plant food once a week. After four weeks he measures the height of every plant.

   • AGroup A, which gets no plant food
   • BBoth groups, because they get the same water
   • CNeither group, because the seeds are the same
   • DGroup B, which gets plant food
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   Resposta: A. Group A, which gets no plant food

   The control group gets everything except the treatment being tested, so Group A is the control.

9. Pergunta 9 de 16

   Why did Jordan put the pots into the two groups randomly?

   Jordan plants 40 bean seeds in identical pots with the same soil. He randomly puts 20 pots in Group A and 20 in Group B. Both groups get the same light and 100 mL of water every two days. Group B also gets plant food once a week. After four weeks he measures the height of every plant.

   • ASo that he would not need to measure the plants
   • BTo avoid choosing the best seeds for one group
   • CSo that Group B would be sure to grow the tallest
   • DTo make all of the plants grow faster and taller
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   Resposta: B. To avoid choosing the best seeds for one group

   Random assignment limits bias. Jordan cannot, even by accident, give one group the best seeds.

10. Pergunta 10 de 16

    Which is the best testable question for a science fair?

    • AIs bouncing a ball good or bad for a person's mood?
    • BWhy are balls so much fun to play with at recess?
    • CDoes drop height change how high a ball bounces?
    • DAre basketballs better than soccer balls for kids?
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    Resposta: C. Does drop height change how high a ball bounces?

    A good testable question names something you can change (drop height) and something you can measure (bounce height).

11. Pergunta 11 de 16

    Which statement is written as a hypothesis?

    • AIf bread is kept in the fridge, then it will grow mould more slowly, because cold slows mould growth
    • BI like the taste of bread from the fridge better than bread kept on the counter in a bag
    • CBread that has mould on it should be thrown out, because some moulds can make people sick
    • DBread is one of the most common foods eaten in Canada, and it is sold in every grocery store
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    Resposta: A. If bread is kept in the fridge, then it will grow mould more slowly, because cold slows mould growth

    A hypothesis is a testable prediction with a reason. "If… then… because…" is a common way to write one.

12. Pergunta 12 de 16

    A student notices that a puddle in the sun dries faster than a puddle in the shade. Which prediction is based on this pattern?

    • APuddles that are in the shade will never dry up at all
    • BWet clothes hung in the sun will dry faster than in the shade
    • CClothes hung outside will always dry faster at night
    • DShade makes water heavier, so it cannot rise into the air
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    Resposta: B. Wet clothes hung in the sun will dry faster than in the shade

    A prediction applies an observed pattern to a new situation that can then be tested.

13. Pergunta 13 de 16

    Tariq tests which paper towel brand holds the most water. He uses a full sheet of Brand X and a half sheet of Brand Y. What is wrong with his test?

    • AHe compared two different brands of towel
    • BThe sheet size was not kept the same
    • CHe measured how much water each one held
    • DHe used paper towels instead of cloth towels
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    Resposta: B. The sheet size was not kept the same

    Sheet size is a variable that affects how much water is held. It should be controlled so only the brand changes.

14. Pergunta 14 de 16

    Why should each test in an experiment be repeated several times?

    • ATo keep going until you get the answer you expected
    • BTo check results are consistent and reduce one-off mistakes
    • CTo change the independent variable a little each time
    • DTo make the data table longer and more impressive
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    Resposta: B. To check results are consistent and reduce one-off mistakes

    Repeated trials show whether a result happens again. Averaging them reduces random error.

15. Pergunta 15 de 16

    A researcher wants to know how much sleep teenagers in Alberta get. She surveys only students at one school's early-morning hockey program. What is the main problem?

    • AStudents in hockey programs are not counted as teenagers
    • BThe sample does not represent all teens in Alberta
    • CSurveys are not a method that can collect science data
    • DThe sample was chosen in a way that is far too random
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    Resposta: B. The sample does not represent all teens in Alberta

    A sample should represent the whole group. Early-morning athletes may sleep differently from other teens.

16. Pergunta 16 de 16

    A student tests whether music helps people do a puzzle faster. Each person does the puzzle first in silence, then with music. Which change would most improve the design?

    • AUse a different puzzle of equal difficulty the second time
    • BStop timing the puzzles and just ask people how they felt
    • COnly test people who say they really love listening to music
    • DLet each person pick any puzzle they like from a shelf
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    Resposta: A. Use a different puzzle of equal difficulty the second time

    People get faster the second time they do the same puzzle. Using an equal but different puzzle removes this practice effect.

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