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Essential Science for Teachers: Physical Science

Density and Pressure Interactive Activity: 5-Question Survey

5-Question Survey: Density and Pressure

The series of questions presented in this activity will help you find out your ideas or your students’ ideas about matter. As highlighted in this video series, when we articulate our misconceptions, we are taking the first step to rectifying them.

Surveying is one of many educational strategies that teachers can use to elicit ideas. Even a brief survey, such as the one presented next, can provide a learning opportunity for students and teachers alike. Students can reveal their misconceptions for the first time as well as open their minds to accepting scientific points of view. Teachers can form a basis for making instructional decisions, whether to validate students’ correct yet unsure ideas, confront student misconceptions, reinforce ideas that are forming, or complement ideas that are accurate but only partial explanations.

When viewing the answers to each of the survey questions, you will also see how others answered the questions.

Before you complete the survey, please identify who you are (pick just one):

I am a teacher. I instruct:
 Grades K-2
 Grades 3-6
 Grades 7-12
 College students


I am a student. I attend:
 Grades K-2
 Grades 3-6
 Grades 7-12
 College


I am a member of the general public


Survey Question 1

A solid rubber ball sinks when placed in water. What will happen if the ball is cut in half and one of the smaller pieces is placed underwater?

 A. The smaller piece will rise.
 B. The smaller piece will sink.
 C. The smaller piece will stay motionless.
 D. The smaller piece will dissolve.
 E. There is no way to predict what will happen.


Survey Question 2

A pebble is dropped into a cup of water and sinks to the bottom of the cup. A solid plastic bead of the exact same weight is dropped into the same cup but floats on the top of the water. What can you say about the pebble?

 A. The pebble is made of the same material as the bead.
 B. The pebble is the same size as the plastic bead.
 C. The pebble has the same mass as the water.
 D. The pebble is denser than the plastic bead.
 E. The pebble can’t be compared to the bead or the water.


Survey Question 3

A pebble is dropped into a cup of water and sinks to the bottom of the cup. A solid metal bead of exactly the same size is dropped into the same cup and sinks to the bottom of the cup. How do the pebble and the metal bead compare?

 A. The metal bead and the pebble have the same density.
 B. The metal bead and the pebble are the same mass.
 C. The metal bead and the pebble are denser than water.
 D. The metal bead and the pebble contain the same materials.
 E. The metal bead and the pebble are as dense as the water.


Survey Question 4

A solid cube of unknown material has a mass of 10 grams. It has a volume of 4 cm3. The material has a density of:

 A. 2.5 g/cm3
 B. 40 g/cm3
 C. 2.5 grams
 D. 0.4 g/ cm3


Survey Question 5

If the cube in question 2 were not soluble in water and were placed in a swimming pool, it would:

 A. sink.
 B. float.
 C. stabilize somewhere between the surface and the bottom.
 D. be impossible to predict what the cube would do.


Now that you’ve completed the survey, make sure to read the closer looks, if you haven’t already, to learn more about these topics.

Answer 1

The answer is B: the smaller piece will sink. Because it sank, we know that the original ball was more dense than the water it is in. Although the smaller piece is now a new shape and size, these are extensive properties that don’t affect the density of the material, which is an intensive property and determines whether it will rise or sink.

Answer 2

The answer is D: the pebble is denser than the plastic bead. Although the plastic bead and the pebble are the same weight, weight is not the determining factor in rising and sinking. It is an object’s “weight for size,” or density, compared to the density of the fluid that it is in that predicts whether it will rise or sink.

Answer 3

The answer is C: the metal bead and the pebble are denser than water. While they may have the same density, and may even contain some of the same materials, the only thing that can be said for sure from the evidence given is that they are both denser than water.

Answer 4

The answer is A: 2.5 g/cm3. As stated in the video density is calculated by dividing mass by volume.

 

Answer 5

The answer is A: the cube would sink. As stated in the video, water has a density of 1 g/cm3. Since the desnity of the cube is 2.5 cm3, it is more dense than water, and will sink.

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Essential Science for Teachers: Physical Science

Credits

Produced by Harvard-Smithsonian Center for Astrophysics. 2004.
  • Closed Captioning
  • ISBN: 1-57680-749-5

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