The arrow takes U turn with a glass of water:
This expeirment can be done with a glass of water.The photo above is made of 2 photos taken one after the other. Left taken when the glass (with water) is not in front of the arrows. The right photo is taken after the glass with water is placed in front of the arrows drawn on the paper. At least 2 principles of classical optics are working here.
Class 8th or 9th students should be able to explain it. There are a few more (at least 2) finer points here.
The idea first appeared here
https://twitter.com/PhysicsNews/status/670278454236078080
