Tubes of different sizes provide lots of opportunities for using the hands to explore and experiment.
Document tubes are great for this as they can be sealed at one or both ends. Most stationary stores have an assortment of different sizes.
Make a rattle
Seal the tube at one end, put a block, a ball or some rice into the tube and seal it at the other end. Watch your child move the tube to explore the sounds that come from inside.
A posting game
Seal one end of a tube and use it as a posting container. The child needs to figure out how to hold the tube with one hand and position the opening so the a block or ball can be posted into it.
Here you see Toesies at 15 months posting blocks into a tube. This requires good planning to align the opening of the tube with the block in the hand.
Tubes make a great bat for knocking over plastic bottles.
Place several plastic bottles on the floor and a little distance apart.
Show your child how to knock the bottles over using the tube as a bat.