How many lights don't need to be on?

Dear Parents,

I have asked that you open this letter at 7:00 PM so that everyone will do this activity at the same time. Go around the house with your child and count how many lights are on which are not being used and could be turned of to save energy. Write the number below and send it to school tomorrow.

I found ________ lights on in my house which could have been turned off.

Name ________________