Children at key stage 1 find total blackout frightening and rarely or never experience it. I wanted to make it less intimidating but still give them enough experience of darkness to be meaningful, but how can you show young children the absence of light?

Using a shoebox, Iplace an object inside and make a small hole in one end, and then ask the children to guess what’s inside. They always seem surprised when they cannot see it. However, it’s still difficult to prove that there is no light inside the box because, of course, as soon as you take off the lid to look, there is.

I enlisted the help of my computer and a portable data logger, a natty little gadget for measuring temperature, sound or light levels. You can demonstrate light intensity on the screen as shades of grey to black, a graph, a meter or numerically. The sensor can be used remotely and can be set to record at intervals.

The children were especially excited watching the numbers change as the light intensity varied when we put the sensor in different places, and I was able to show that there was no light at all inside the box. When we introduced light, which of course the sensor detected immediately, we were able to see the object and link the cause and effect. It helped the children understand that you could not see an object without a light shining on it.

Older children can be encouraged to draw a diagram showing the path the light travels inside the box or make a graph showing light intensity in different places.

Another misconception children often have is that shiny objects give out light. By using different materials at the opposite end of the box to the light source, I demonstrated not only that they did not emit light but that some were better reflectors than others.

Caroline Palmer, Year 1 class teacher and primary science advanced skills teacher, St Clement’s and St John’s Infant School, Bournemouth