# A pattern of use

Combine:

- showing how much power (the watts or kilowatts to run a bulb or toaster) with an arrow
- showing how long the appliance is on for (the hours in a day) with a pie.
- connecting the power and time to the energy you'll pay for using a cost box
- showing how much energy you have to pay for with an bar (the kilowatt-hours)

to describe a day's use.

### Describing a pattern of use

use these three:

- durations – how long: the hours
- power – how much you're demanding: the kilowatts
- cost boxes - a combination of how long and how much you're demanding: the kilowatt-hours

to build a description of a day's use of electrical devices.

###

You pay for the the kilowatt-hours you demand over the day. Add the areas of the cost boxes to find out the total.

Each cost box shows how much energy you demanded in that slot, so stacking the energy bars also calculates the cost.