First of all, think active movement and voices. Writing them up can be set up in a format such as :1. Activity name and materials needed,2. Age group and intended skill reinforcement, 3. Instructions for the activity and time limits. 4. Anything else you think should be included. Infants like textiles to touch, clapping their hands, watching you touching your nose and teaching them to touch their nose, all in time to a basic music beat such as beating a small drum or playing baby music. Toddlers love to march, crawl, run, anything to move. Use music with a clear beat and call out what to do. Then call on one of them and ask if it should be march or crawl. Give them only two choices. With preschoolers, you can get more complicated, playing a song which has them shout out the chorus phrase, hop like frogs, make noises like the animals on old McDonald's farm or use Raffi's music for little kids which has lots of things to do. For kindergartners, you need to decide what you need to teach with your exercises to music. Create your own goals and find music and make up activities which relate to your goal. You need to show organization, purposeful activities, write directions any teacher could follow, and have goals written and a way of measuring if you achieved your goal of having kindergartners all participate or all follow one direction at a time. Good luck and what a great assignment!
I work at a preschool and once a week we have a music teacher come in and conduct a music session followed by a story time. She has a theme for each week (ie: Pirates) and has a simple song with repetitive words for the young children to catch on to. All the songs have specific actions to go with the words. The kids learn to connect the action to the words which helps them remember the songs.