See if you can find 5 net gift bags. 

20cm  x 26cm seems a good size.

 

If you give these to your child to play with they will enjoy trying to open them and then pulling the draw string again.

Allow total free play and see what your child does.  They will probably want to put little things in them.

 

To direct their play ask your child to put one toy into the first bag, 2 into the second, 3 into the third, and so on.

OR

You can put a certain number of toys in each bag and then see if your child can work out how many toys are in each bag.