Use the responses to the hinge question to guide children to one of three levels of discussion.

👣 What demands power in your home? Can you work out how much it costs? 👣

🩺 One or other facet is likely to be seen to dominate, and you'll probably have to encourage children to make the data collection exercise their own.

I can just ask.

The electricity bill will tell us.

Maybe you can tell us what to write down.

🔎 Start diagnostic and exploratory discussions using thoughts like these:

List the kilowatts and hours for everything.

Yes, but just the time it's on, so we can work out the kilowatt-hours.

Then we'd need how much each kilowatt-hour costs.

🩺 Children will be more willing to devise strategies and consider a wider range of ways of recording the necessary data.

We'd need to make a list...

...and find out the power of everything on the list

...and find out how long it was on for.

🔎 Start diagnostic and exploratory discussions using thoughts like these:

we have to record how long and how much power for everything.

We'd better record everything in kilowatts and hours.

What do we do with all the kilowatt-hours we've worked out?

🩺 Children draw on other data recording exercises and discuss both facets and how they will be recorded.

Write down how long each on is on for, and it's power.

Then we could use these quantities to find what each one costs.

Does it matter that each unit costs different amounts at different times?

🔎 Start diagnostic and exploratory discussions using thoughts like these::

we'd need to draw out a table to record how much power and for how long

would it help to put the most powerful things or those things on for longest at the top?

Don't forget the third column of the table for working out the kilowatt-hours.