I only worked as a high school chemistry teacher for only 2.5 years, but I think experiments especially quite spectacular ones if you can engineer them, are always the way to go.

I'm a strong believer in:-

I hear and I forget.

I see and I remember.

I do and I understand.

If you can perform entertaining experiments/demonstrations, they'll remember them, film them on their phones (if you allow that) send them to their friends and talk about it.... and you can bet they'll remember it after that.

Here's a link to a Hess's law demonstration/experiment I devised.

https://www.chemedx.org/blog/experimental-demonstration-hesss-law

Philip, thank you so much for your answer.

I still remember many of the experiments that I conducted in high school chemistry and physics, and that was over 40 years ago. My instructor in those classes was a very passionate experimentalist and I can definitely that he was a key influencer on my educational and career path.

I only worked as a chemistry teacher in high school college for about 3years, the work experiment then are quite interesting to the students