Power Choices at the Park Leaf Shed

Moving Leaves at Linden City Park

At Linden City Park, workers use a small cart to move bags of fallen leaves from the leaf shed to a compost area. The park is considering a cart powered by gasoline or by a rechargeable battery. One class investigates sunlight as a possible energy source before reviewing the park's plans.

Step 1: The class places a level board in a sunny spot and marks a starting line. An adult checks a small solar model cart. Its panel changes sunlight into electricity that runs its motor. The model has no battery.

Step 2: Students place the model at the line with its panel in direct sunlight. They let it move for 10 seconds and measure its travel distance in centimeters.

Step 3: Students return the model to the line. An adult holds a wide card above the panel to put the panel in deep shade. The card does not touch the cart. Students again measure the distance traveled in 10 seconds.

Step 4: The class repeats both conditions, alternating sunlight and shade. Students keep the cart, board, starting line, and test time the same. The sky stays clear. The graph shows their four measurements. Students do not handle or test fuels.

Energy notes: Gasoline is made from petroleum, also called oil, pumped from underground. Coal is dug from the ground and can be burned at a power plant to make electricity. That electricity can charge a battery. Petroleum and coal formed over millions of years. People use them much faster than new supplies form.

Sunlight is a natural energy resource that is renewed each day. Solar panels can charge batteries for later use. Panels do not burn fuel while making electricity, but making panels and batteries requires mined materials. Mines and oil wells can disturb habitats. Burning gasoline or coal releases air pollution and gases that contribute to warming. A battery cart has no exhaust while it runs, but charging its battery may involve burning fuel somewhere else.