As an introduction to the unit, we will begin with a discussion of the question: what is energy? The class will complete a KWL chart in which they will list what they know about energy and what they want to know about energy. The third column, which lists what they have learned about energy, is not filled in until the conclusion of the unit. In talking with my students about this, I found that energy immediately evokes the power and strength that they get from the food they eat. There is also recognition of cars, and their reliance on gas, as well as light bulbs, being powered by electricity.
A few terms need to be defined as the unit begins: energy, work, force, and power. Energy is the ability to do work. In physics, work implies that there is movement. To do work, there needs to be some sort or energy used usually some kind of push or pull. It is energy that keeps us alive and the world moving. Students will learn about two types of energy: stored or potential energy, and working, or kinetic energy. Students can understand these concepts through examples like batteries, and their own bodies which eat food for energy but store the energy until they need it to run or talk, etc.
Using the example of a batter in baseball, we see that before he swings the bat it has potential energy. When the batter does the work of swinging the bat, energy is within the bat. When the bat hits the ball, the bat works on the ball and changes its stored energy into kinetic or working energy. The result is that the bat hits the ball and it flies off. The concept of power would be related to how hard you hit the ball.
Bat (potential energy) → Batter swings the bat (applies energy) → Bat hits ball (work is done on the ball) →Ball flies out