Sort results visually and use side-by-side diagrams to contrast series and parallel.
Colour-coded results table
As students test materials, they shade each row green for conductor (globe lit) or amber for insulator (globe dark). The finished table shows at a glance that metals cluster green and non-metals cluster amber.
Side-by-side circuit diagrams
Give students two pre-drawn diagrams — one series, one parallel — and have them mark, in red, what happens when one globe is removed: in series, cross out all globes; in parallel, cross out only the removed branch. The visual contrast makes the difference unmistakable.