Run a longer term switch-off campaign at school (eg Switch Off Fortnight)

50 KS1 KS2 KS3 KS4 KS5
The nationwide Switch Off Fortnight campaign is co-ordinated by EDF Energy's The Pod.
You can enrol to join Switch Off Fortnight, which gives you access to lots of free resources.
A quick guide to Switch -Off Fortnight can be found here