Rainbow Density Column
Three related teacher demonstrations: Rainbow Density Column, Disappearing Clear Beads, Arrow Reverses Through Water.
Teaching & key ideas
1. Rainbow Density Column
Materials: Clear cylinder; several safe liquids of different densities
What you do: Layer liquids slowly.
What students see: Distinct layers form.
Question: Which liquid should go on the bottom?
2. Disappearing Clear Beads
Materials: Clear water beads; water; clear container
What you do: Place hydrated clear beads in water.
What students see: Beads seem to disappear.
Question: Are the beads still there?
3. Arrow Reverses Through Water
Materials: Bold paper arrow; round clear glass/cylinder; water
What you do: View arrow through empty then water-filled cylinder.
What students see: Arrow appears to reverse direction.
Question: Did the arrow turn around?
Lesson flow
Predict → observe three demonstrations → compare what changed → choose independent activity station → cleanup/share.
Guiding questions:
Question: Which liquid should go on the bottom?
Question: Are the beads still there?
Question: Did the arrow turn around?