Workshop prep and a riddle

Looking at the picture below, can you guess which experiment I am going to do at the workshop? Yep, my favourite experiment — melting ice cubes! :-)

And I am obviously prepared for several extensions of the classic experiment should the students be so inclined…

Now I only need to get the ice cubes from Kiel to Hamburg — and as ice cubes, not a colourful, salty, wet mess :-)

Having gotten that backstory as a hint, any idea what’s going on with the spoons below?

Yep. Freshwater on the left, salt water on the right. Different refraction indices due to different densities. Neat :-)

One glance — do you know which of the bottles is empty?

The other day I was sitting in my conservatory with a friend when I had to take the photo below:

Can you see how one bottle refracts light and the other one does not? What does this tell us about whether there is water in either of those bottles? I met most “normal” people wouldn’t even notice a difference.

I know, I’m a nerd, but I have so much fun “discovering” small stuff like that! :-)