To illustrate how quantum superposition and measurements work one can use a smartphone 📱 and two pairs of 👓 3D glasses 👓 to measure the emitted polarized light in different basis successively. What other simple experiments one can do to illustrate quantum principles ? 🧪⚛️

The photoelectric effect is a pretty simple setup, and is cast-iron proof that light is quantised. (Of course it is - it’s the experiment that started the whole quantum revolution).