If you have a young assistant around the house who's interested in helping out with projects, you may wish to give them a little practice time with basic, blunt hand tools.
Hammering sharp nails into a block of wood with a heavy hammer is a dangerous prospect for a child. With careful supervision and the right materials, however, your child can hammer nails, too.
A block of rigid foam insulation is a great surface for nail hammering practice. It's soft enough that nails can easily go into it, and it won't allow fingers to get pinched.
Bracket framing nails make excellent practice nails. They're short and stout, with wide heads, so they're easy for kids to hammer.
You may want to make a little starter hole in the block. In no time at all, and with your supervision, your young assistant will have perfect, and safe, hammering technique!