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

👣 How does what you pay depend on what you switch on? 👣

🩺 Again, starting out, you're likely to find children latching onto a single line of thinking, considering one facet of the question.

Turning on a big thing costs heaps.

It's the things that are turned on for longest that cost you.

Even little things turned on for a long time cost you.

🔎 Start diagnostic and exploratory discussions using thoughts like these:

Find out how long and how powerful. Put them together to figure out the cost.

How do you

put them together?

On for longer and demanding more when they're on...

🩺 Children may appreciate that there are multiple facets to the question, but require significant support to work out how to combine these facets.

Both little and big things turned on for a long time cost you.

But does a little one turned on for a long time cost more than a big one turned on for a short time?

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

Combine power and how they're on for to find the cost.

How do you

put them together? Add, times?

The clue is in what you get charged for.

🩺 Children appreciate the place of numbers in the discussions, and recognise that there is interplay between the different numerical descriptions: that numbers giving the magnitudes of two different quantities both contribute.

How long and how powerful — both with numbers.

Power and hours. Put the two together.

Kilowatt-hours is what you get charged for. So you have to figure those out.

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

Figure out the cost from m power and from time on.

How many watts tells you something, but you also need to think about time.

Kilowatt-hours. Just look at the name and think of boxes.