Blue Sky and Sunset
A beam of white light is shined through a tank of water containing hypo. When HCl is poured into the solution, blue is scattered and red is passed through.
Try dropping a couple of creamer into water and mix them will get some results.
Sodium Thiosulfate (Na2S2O3): 12.67g
Hydrochloric (HCl): 15.78g
Slide Projector with a Slide of a hole
Dissolve Sodium Thiosulfate in water and pour Hydrochloric into it. Using a chopstick give a little stirring.