Musical games are a great way to build developmental skills. One of my favorites is the "Magic Dot" which is an activity that develops attention, impulse control, awareness of others and following directions. For my magic dots I purchased these athletic markers from Amazon.com however you can use anything as a visual cue.
To introduce the magic dot, I start with one dot. I'll pass out drums (could be any instrument) and show the kids that the dot is magic because every time I touch my foot to the dot, the drums sound. Sometimes I tap my foot very gently and to indicate drumming soft, sometimes I jump on the dot for a loud bang, other times I might hover my foot above with the kids waiting in anticipation for me to tap the dot, mallets hovering over their drums and poised to strike. When the group has mastered one dot I'll introduce a second dot (and sometimes even three!).
The second dot could also be another instrument such as shakers and I will take half the drums and pass out shakers. I will show the group which dot is drums and which is shakers. There is so much you can do with this game. The dots could be different movements such as clapping, patting, stomping or jumping. If the group is ready to have a peer be the leader this is such a fun way to develop self esteem, leadership skills, and attention to others. If you do feel your group is ready for this I recommend starting with one dot.
As you can imagine, there are a ton of variations on this! I won't list them all here but if you'd like any more ideas on how to use "magic dots" send me an email and I'd be happy to share more!