A is for Atom
This animated film from 1953 is charming. It’s an unashamedly didactic film, but done with wit and style. It contains a lot of material that students are required to learn at GCSE. In may ways, it’s better than some of the more recent films that cover this material and I feel it’s worth showing for the historical content alone (something that is often missing from modern textbook treatments).
If your students can get over giggling at the 1950s narration, I think they’ll find this a really interesting and useful film to watch. At about 15 minutes long, it’s a little long, but a question sheet would help ensure that it would be time well-spent. I’d recommend a film like this for use in an end of topic summary lesson.