Did you know that liquids are stackable? It’s possible because liquids can have different densities: some are thicker/heavier while others are thinner/more light.
From YouTuber Brusspup, watch how to make your own Liquid Stacking experiment:
an empty bottle (with a lid)
a measuring cup
dark corn syrup
dish washing liquid
water (add food coloring)
rubbing alcohol (add food coloring)
And you can add two more layers if you have some honey (most dense) and lamp oil (least dense).
The video notes recommend not turning it over too much for fear of the colors getting muddied, but isn’t seeing what happens when they mix really the second half of the fun? The kid should do this!