Worksheet

New Wheels for the Loaner Boards

Grade 7 physical science: trace urethane skateboard wheels to crude oil and plant oils, analyze a roll test and weigh the effects of synthetic wheels.

Grade 7ScienceInteractive · Printable

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1 NGSS standard
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10 questions
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Format: Interactive · Printable
Grade: Grade 7
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Short answer

About this worksheet

What students practice

Students explain how a synthetic polymer is made from crude oil or plant oils through chemical reactions.
Students use test data and the passage to weigh benefits and costs of a synthetic material to society.

How to use

Read the passage together and check the roll test setup, then have students choose wheels in question 10 and compare their choices in small groups.

Curriculum

NGSS standard covered

MS-PS1-3

Explain how synthetic materials, such as plastics and medicines, are made from natural resources and affect society.

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New Wheels for the Loaner Boards

Trace skateboard wheels to their natural resources and weigh their effects.

What a skateboard is made of

Read the passage, then answer the questions.

The Board Shop at the Youth Center

1The youth center in Eastlake has a small board shop where teens fix up donated skateboards and lend them out. This fall, volunteer Ms. Ngaio Parata asked seventh graders Jun-ho Park and Amaru Quispe to choose new wheels for the center's 30 loaner boards. First, she asked them to find out what each part of a board is made of.

2A deck is made of thin layers of maple wood. The wood is cut and dried, but it is still wood, a natural material. The layers are pressed together with a synthetic glue. Grip tape on top of the deck is a plastic film with a sticky back and a rough, gritty top.

3The first skateboards, in the 1950s and 1960s, often rolled on steel or clay wheels. These wheels slipped on smooth ground and rattled over every crack. In the early 1970s, wheels made of polyurethane, often called urethane, appeared. Most polyurethane is made from chemicals that come from crude oil or natural gas, which are natural resources. At a chemical plant, small molecules made from these chemicals react and link into long chains. The result is a new substance that is not found in nature. While it is still a thick liquid, it is poured into wheel-shaped molds, where it hardens. Urethane wheels gripped the ground and rolled smoothly over small cracks, and they are often credited with helping skateboarding become much more popular.

4Today, some wheels are made partly from plant oils, such as castor bean oil, instead of only from crude oil. The plant oil is changed into new substances by chemical reactions as well. Polyurethane also has costs. Crude oil and natural gas are nonrenewable. Some of the chemicals used to make polyurethane can harm workers' lungs, so factories must handle them with care. Urethane breaks down very slowly, and most worn-out wheels end up in landfills.

5To compare wheel sets, Jun-ho and Amaru strapped a 20 kg sandbag onto one board instead of a rider. For each set, they let the board go from the top of the same short ramp and measured how far it rolled on smooth concrete and on the cracked asphalt path behind the center. They ran three trials for each set and recorded the average.

Use paragraph 3. Complete the steps for making a urethane wheel.

Word bank: resource · react · chains · molds · dissolve · atoms

Crude oil is a natural . At a chemical plant, small molecules made from it and link into long . The thick liquid is poured into , where it hardens into wheels.

Use paragraphs 2 and 3. Which part of a skateboard is a natural material?

A. The grip tape, because its top feels rough like sand
B. The urethane wheels, because crude oil comes from the ground
C. The glue, because it holds layers of wood together
D. The maple layers, because they are cut and dried but still wood

Amaru says the plant-based wheels are a natural material because they start with castor bean oil. Use paragraph 4. Why are they still a synthetic material?

A. The oil is pressed from beans, which changes its color from yellow to white.
B. The plant oil is mixed with sand, which turns it into a solid wheel.
C. The plant oil goes through chemical reactions that form new substances.
D. The castor beans are grown on farms, and farm crops count as synthetic.

The roll test

Use Table 1 and the passage to compare the wheel sets.

Table 1. Roll Test With a 20 kg Sandbag (average of 3 trials)
Wheel set	Made mainly from	Smooth concrete (m)	Cracked asphalt (m)	Price for 4 wheels
Hard urethane	Crude oil or natural gas	16	7	$28
Soft urethane	Crude oil or natural gas	13	11	$32
Plant-based soft urethane	Castor oil and crude oil	13	10	$40

Use Table 1.

On cracked asphalt, the soft urethane wheels rolled m farther than the hard urethane wheels. On smooth concrete, the hard wheels rolled m farther than the soft wheels.

Which statement best describes the pattern in Table 1?

A. The hard wheels rolled farthest on smooth ground, and the soft wheels rolled farthest on cracked ground.
B. The soft wheels rolled farther than the hard wheels on both kinds of ground in the test.
C. The wheels made partly from plant oil rolled farther than the others on both kinds of ground.
D. The more a set of wheels cost, the farther it rolled on both kinds of ground in the test.

Each board needs one set of 4 wheels.

Buying plant-based soft wheels for all 30 loaner boards would cost $ more than buying soft urethane wheels made from crude oil.

Underline each statement that describes an effect of synthetic urethane wheels on society or the environment.

They rolled smoothly over cracks, which helped skateboarding grow more popular.The layers of a deck come from maple trees.Most worn-out wheels end up in landfills, where they break down very slowly.Grip tape has a rough, gritty top side.Making them uses up crude oil and natural gas, which are nonrenewable.

Ms. Parata asks what would change if the shop switched from soft urethane wheels to plant-based soft wheels. Which answer is best supported by paragraph 4 and Table 1?

A. Worn wheels would rot in a few weeks, so the shop could put them in its compost bin.
B. Less crude oil would be used, but worn wheels would still break down very slowly.
C. The boards would roll much farther on the cracked path behind the youth center.
D. The wheels would be made on farms instead of in chemical plants, so they would cost less.

Use paragraph 3. Which change in skateboarding is best explained by the switch to urethane wheels in the 1970s?

A. Boards became easier to ride on rough ground, so more people took up skating.
B. Skateboards became cheaper, because steel and clay cost more than oil.
C. Decks became lighter, because urethane replaced the maple wood layers.
D. Grip tape was no longer needed, because the wheels gripped the deck instead.

10.

Most loaner boards are ridden on the cracked asphalt path from the youth center to the park. Which wheel set should the shop buy? Write a claim, use data from Table 1 as evidence, explain what natural resource your choice is made from and how it becomes a synthetic material, and name one cost of your choice to society or the environment.