To me, testing with a light is like trying to tell time by asking someone if the sun is up.

A usable meter can be purchased for little more than 5 bucks - a pretty good one for 25.

Some come with instruction booklets.

A great way to learn how electricity works is to purchase a kit to do experiments.

With a decent kit, you can replicate almost any automobile electrical circuit.

With some experiments from a booklet, some of his own experiments, and repetition, my 8-year-old grandson learned some things that I did not expect him to do. I did have to monitor him so that short circuits did not kill his batteries.