This page will be interesting for kids to look at with all of its facts in an interesting layout, and two short videos (the second is about Africa, not Mansa Musa). This video, at four minutes, is a more extensive version of the first video. Access National Geographic's videos on Mali here.
Here's a link to the first few informative pages of an e-book for kids with a magazine layout (you need a membership to view the entire book). This is a succinct summary of his life from an article in World Book Kids, and another with a comprehension question at the end. For older kids or research projects, here's a more lengthy explanation, along with cultural notes on the Kingdom of Mali.
I'm not aware of how lessons for older children are structured at Comm. Central, but here's a thorough lesson plan and student page for older students.