Week 3

Session 2

Guiding Question

  • How can we make sand stand tall?

Subquestions

  • How does sand support buildings?

Outcomes

  • Learners will explain that the particle interaction (friction and density) makes the sand strong.

CT Components

CT Vocabulary

  • Friction, density, sand sizes (angular, round)

Data Collection

  • Sandpaper (different sand shapes); speeds of cars

Data Analysis

  • Relation between friction (different sandpaper) and speed of the car

Problem Solving

  • Test & hypothesize experiment results

Entry Event

10 minutes

Facilitator asks “what is friction?” Have several students explain it. Then facilitator says “We are going to learn about friction today” and then hands out the worksheets. Facilitator plays and asks student to write notes on the worksheet.

Facilitator leads a discussion on friction. Facilitator has students come up with some examples of friction in their daily life first. Facilitator then asks students how sand can support buildings. Students would provide some answers. Facilitator gives students two pieces of sandpaper and asks students to rub them together to feel the friction. Students record their observations on the worksheet.

Part 1

Sandpaper Board Activity

Small-group Hands-on Scientific Inquiry 30 minutes

The facilitator says we will explore friction more in this activity. We will test 4 different sandpaper boards and see on which sandpaper board, a block can slide down the fastest. The facilitator asks the following questions to get students thinking:

  • What affects the speed of the block sliding down the sandpaper boards?

  • What could be changed on the boards to make block slide faster?

Directions

  1. Students observe and draw the sandpaper boards first (in terms of the size and shape of the sand) on the worksheet.

  2. Lean all the sandpaper boards on the wall (the starting height should be the same for each sand board)

  3. Before testing each board, students predict which board will produce the fastest block.

  4. Students should be organized into “teams” to cheer for their board.

  5. Select two students to test-run the blocks by sliding them down each of the four sandpaper boards.

  6. Students should repeat these tests five times (for validity) and document the results within their journals. An adult needs to help with timing the block.

  7. Once all tests have been completed, have student discuss their findings and hypotheses in small groups.

Resources

  • 4 sandpaper boards - glue 4 types of sandpapers on boards.

  • Some solid blocks (wood or plastic)

  • Timer (use cell phones as timers)

  • Sandpaper Boards Worksheet

  • Adults to supervise/assist this activity

Whole Group Discussion

10 minutes

Facilitator can ask these questions to help guide the discussion:

  • On which sandpaper board will the block slide the fastest?

  • Why?

  • What would happen if we arrange the sandpaper boards from fast to slow?

  • What affects the speed of the block sliding down the sandpaper boards? (size of the boards, and height, if kids do not talk about the surface of the boards, direct kids to observe the surface of the boards if surfaces do not come up)

  • What could be changed on the boards to make block slides faster? How does this apply to sand?

10 minute break

Part 2

Sand in a Jar

Small-group Hands-on Scientific Inquiry 20 minutes

Grounded (chp. 20)

Facilitator asks “What makes sand strong?” Facilitator takes some ideas from students. Then facilitator helps students relate the sand strength with the friction activities. And facilitator says that “We will explore some factors that make sand strong in this activity.

Setup Procedures

  1. Place about a quart of dry sand on the table in a pile.

  2. Place the other quart of dry sand in the container.

Directions

  1. Put the weight on the sand pile and observe the behavior.

  2. Put the weight on the sand in the jar, and observe the behavior.

  3. Push a rod into the pile of sand on the table

  4. Try to push the rod into the sand in the container.

  5. Have students document their observation. Have students explain their experience.

Resources

One quart jar (use the same jar used before)

Two quarts of dry sand

Weight

A form tray

Plastic or wooden rod

Sand in a Jar Worksheet

Whole Group Discussion

10 minutes

Facilitator can ask these questions to guide the discussion. This activity brings density and friction together. Facilitator can ask:

  • What did you observe when you put the weight on the sand pile?

  • What happened when you put the weight on the sand in the jar?

  • How did you feel when you push a rod into the pile of sand on the table?

  • How did you feel when you try to push the rod into the sand in the container?

  • What makes sand strong?

Facilitator can explain that because of the nature of the soil, its strength not only depends not only on particle roughness (friction) but also how close they are to each other (density).

End of Session Reflection and Debriefing

5-10 minutes (will be recorded)

  • What did I learn today?

  • What worked well?

  • What didn’t work well?

  • What can I/we do differently next time?

  • Do you have anything else to share?