With your students opposite you or in a circle, ask them to copy you. As you follow the steps outlined here you will all say the words in the volume that matches their meaning. Pianissimo will be whispered and the others spoken increasingly louder, until fortissimo is laughingly yelled as loud as possible. There are also fun body positions.
Here we go!
Curl your body into a ball on the rug and motion for your students to join you. Since they are curled up and won't be able to see you, so whisper, "ready, go," then together whisper, "pianissimo".