A Lid That Lets You Look
A classroom investigation compares how clear plastic and cardboard let light through to help students choose a lid for their counting-cube box.
Play the quiz as a gameThe counting cubes in a classroom need a box with a lid. But students want to see the cubes without opening it. Which material should cover the box? A material is what something is made of. The class tests clear plastic and cardboard.
The first heading on the class chart is “Light Test.” Students aim a flashlight at a white card. Its beam, or narrow path of light, makes a bright spot. They put clear plastic between the flashlight and the card. A bright spot still appears.
The plastic is transparent. This means light passes through it, and objects can be seen clearly through it. Students can see the cubes through the plastic, too. Next, they put cardboard in the beam. The cardboard blocks the light, leaving a dark area on the card.
Cardboard is opaque, which means light does not pass through it. The cubes cannot be seen through the cardboard. A caption under a drawing says, “Cardboard blocks the beam.” The caption explains what the drawing shows.
Students observe, or watch closely, during each test. They compare the results by looking for what is alike and what is different. Both pieces can cover the box, but they do not let light through in the same way.
The class chooses a clear plastic lid. It keeps the cubes inside while letting students see them. The investigation shows why materials are chosen for different jobs. For this job, letting light through is helpful.