Look at floating/sinking and movement in liquids.
Have a selection of small clear plastic drinks bottles.
Fill them 3/4 full of different liquids.
Water ~ Baby oil ~ Jelly! ~ shampoo
Add different things to each of the bottles
Small world creatures
Button & Beads
Glitter & Sequins
Add a couple drops of food colouring ~ with 7 bottles you could make a rainbow !!!
Glue the caps securely back onto the bottles
Shake / turn upside/ hold on its side and move it gently in a rocking motion.
How do the items move in the liquids?