This would be a fun idea for kids and a great use for all those toilet paper rolls I can't throw away! Chopsticks or tweezers for fine motor skills, used to pick up and drop pom-poms into color matched toilet paper rolls.
These work great! Did them for a school science night using smaller bottles. They look like lava lamps. - Fireworks in a bottle - looks fun and easy! bottle of water, oil, coloring (food coloring, paint), alka seltzer.