The kilowatt-hour previously mentioned is the unit of energy measuring the total amount of electricity that is consumed by a household. Discuss with the students that when we go shopping most items are purchased by the amount we plan on consuming. We wouldn’t buy 100 lbs. of meat for one week. We buy according to what we use. We estimate what we will need and buy accordingly. The problem with electricity is that we consume without considering the cost. Since we cannot see how much we use, we aren’t too concerned about waste. One of the secondary goals of this unit is to create an awareness among our children. The unit will be a cooperative adventure between the students and parents that will help families, especially children, become more responsible for their use or abuse of electrical energy. Hopefully by actually monitoring how much (kilowatts) are being used, a conservative attitude will follow.
As a warm up exercise, have student brainstorm the various units of measurement we use everyday—pounds, inches, ounces, quarts, gallons etc. Have them bring in these items and fill, measure, pile and weigh different substances. Ask them to bring a kilowatt hour in. Is it possible? (Discuss) Then how do we measure how much electricity we use at home?
Have available a number of light bulbs with different wattage. Maybe a toaster, iron, radio also. Ask: How can I calculate how much it cost to run this appliance ? Start with the light bulb. Depending on the level of the group you may use the other appliances or just the light bulb will be sufficient. Distribute “What is a kilowatt-hour?” worksheet.
This exercise can be extended to a variety of other exercises. List the amount of wattage that appliance will use if operated one hour. Check wattage. This lesson could be correlated with your math lessons.
Again the watt is a unit used to measure (rate of producing or using energy). An electric device uses 1 watt when 1 volt of electric potential drives 1 amp of electric current through it. A light bulb operating at 100 volts and using 2 amps consumes 200 watts (100 x 2 amps).
