Mrs. Thorp’s Third Grade Blog

One of the concepts that I taught in third grade science was the difference between a physical change and a chemical change.

• I brought an apple to school. We cut it in quarters. This is a physical change. We let the apple sit out on the counter and saw that it turned brown. This is a chemical change. Of course, we all got to sample apple pieces.
• Making banana bread is another example of a chemical change, but cutting the banana bread into slices is a physical change.
• Freezing lemonade in small paper cups is an example of a physical change. Watching it melt is also a physical change.

When we studied the definition of a mixture (A composition of two or more substances that are not chemically combined with each other and are capable of being separated), we made a trail mix of raisins, cereal, M and M’s. Before we ate it we separated the ingredients, put them back together, separated them and finally put them back together. Repeatedly mixing and separating the ingredients, helped them remember the definition of a mixture.

During our unit on simple machines, a mom of one of my third graders brought in her apple peeler, corer and slicer. Each child had a chance to turn the crank and see all the different simple machines( wheel and axle, wedge, screw) at work.

Once again we enjoyed eating the apples when we were finished.

Let me know if you have any other ideas of using food to teach science concepts.