Parents: being careful to keep your child's fingers out of your workspace, flatten the bottle caps with a hammer.
Draw two wide strips with rounded edges onto the cardboard and allow your child to cut them out using the safety scissors. Fold each in half, so they look like duck bills.
Taking over duties, put a dab of glue on the jagged edge (the bottom) of each bottle cap. Glue one to the top and one to the bottom of the inside of each piece of cardboard so the bottle caps meet when you close the cardboard “duck bills.” Let dry.
Encourage your child to decorate the castanets with markers, glitter, or whatever else he fancies. Let dry.
Hand your child the castanets and show him how to press the upper and lower pieces of cardboard together so the bottle caps meet and click.
Have him position one castanet in each hand and encourage him to create an upbeat rhythm or, if he likes, an entire song!