Testing Materials for Uses

Question 1

A class performed a fair test to compare how quickly three different spoon materials—metal, wood, and plastic—heat up when their handles are placed in a pot of boiling water for 2 minutes. The metal spoon handle became very hot, the wooden spoon handle stayed cool, and the plastic spoon handle became slightly warm but began to soften. Based on this evidence, which of the following is the best reason for choosing a wooden spoon to stir a pot of hot soup?

Accepted Answer

Wood does not conduct heat well, so the spoon stays cool and is safe to hold while stirring hot soup.

Answer

Plastic does not melt when heated, making it the safest material for stirring hot soup.

Answer

Wood conducts heat quickly, allowing the soup to cool faster.

Answer

Metal is the cheapest material, which is why it is used for kitchen spoons.

Question 2

A student wants to find which material—metal, wood, or plastic—is strongest enough to be used for the tiny bridge beams in a classroom model. Which plan would be a fair test to compare the strength of the three materials?

Accepted Answer

Cut three strips that are all 30 cm long, 2 cm wide, and 0.5 cm thick—one metal, one wood, one plastic. Place each strip on the same two supports, then add identical 10‑gram weights one at a time to the middle of the strip until it bends or breaks, recording the total weight for each material.

Answer

Use a 30‑cm metal strip, a 25‑cm wood strip, and a 20‑cm plastic strip; place each on different tables and add the same 10‑gram weights to the middle of each until it bends, then compare the results.

Answer

Take three strips of the same length but make the metal strip twice as thick as the wood and plastic strips; put them on the same supports and add the same number of weights to each, noting which bends first.

Answer

Test the metal strip on a Monday, the wood strip on a Wednesday, and the plastic strip on a Friday, using the same supports and adding the same weights each day, then compare the weights needed to bend each strip.

Question 3

Which plan would be a fair test to find out which material—metal, wood, or plastic—absorbs the most water?

Accepted Answer

Cut three strips that are the same length and thickness (10 cm long). Weigh each strip dry, then place each one in a cup of water for 5 minutes. After soaking, gently pat the surface dry and weigh each strip again. The material that gains the most mass absorbed the most water.

Answer

Weigh each material dry, then pour the same amount of water over each piece and watch which drips the most water when you tilt it.

Answer

Cut a long piece of metal, a short piece of wood, and a medium piece of plastic. Put them all in a bowl of water for 10 minutes and see which looks the wettest.

Answer

Put a metal spoon, a wooden stick, and a plastic ruler in separate jars of water for the same time, but before weighing, shake the water out of the metal piece while leaving the water on the wood and plastic.

Try three questions

A student wants to find which material—metal, wood, or plastic—is strongest enough to be used for the tiny bridge beams in a classroom model. Which plan would be a fair test to compare the strength of the three materials?

Which plan would be a fair test to find out which material—metal, wood, or plastic—absorbs the most water?

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