Let's learn about things that absorb and things that repel liquid!
fabric scraps (various kinds)
containers to hold water
water droppers (we also used baby-ibuprofen-type syringes)
measuring cups and/or spoons
Maisy takes a bath / Cousins, Lucy
This book was a bit of a stretch, but I've always loved the page where Maisy is standing at her front door in her towel, dripping water and it's not easy to search for picture books that specifically include towels!
For one of the classes, I also showed this duck video and talked a little bit about how duck feathers don't get wet but the water just slides right off and why (the ducks have a special oil gland that they use to spread oil over their feathers to waterproof them).
The inspiration for this class (or "what I thought kids might do"):
Little Bins for Little Hands: Water Absorbtion
What Kids Actually Did:
drop water onto various materials and observe absorbtion
observing how water drips through a coffee filter
once again a fascination--figuring out the mechanics of how to use them to pick up water was enough to keep some of the kids busy the whole time transferring water from one container to another.
Adult Challenge of the week: Ask "Why do you think....?" questions to start a conversation with your child about their observations about water absorption.
Hindsight Tip: If you have more than one class session in a day, make sure you have a stash of fabric for each class--they can take a long time to dry and it would be quite easy to predict which materials will absorb water if you can touch them and feel that they're already wet!
Variations to try:--Cotton balls would also be another absorbent material to test.
--You could try soaking some wooden sticks in oil before class and letting them dry and then testing them to see if the oiled ones were more water repellent than non-oiled ones.
The free printable "Does it absorb water?" PDF chart can be downloaded here.