Differentiated learning in the K-5 classroom

My K-5 students were so excited about last December’s Hour of Code that I decided to devote one class a week to Code Studio. Now that we have begun a new school year, I have discovered a new opportunity/problem: my students are at different conceptual levels. In the 1st & 2nd grades, I have some students who did so well in Course 1 that they want to move on to Course 2, while others in the class need and want to take Course 1 all over again because they don’t feel as confident. It is the same for the 3rd and 4th graders, who did Course 2 (but didn’t finish it) last year.

Have any of you encountered this situation? I have responded by teaching/reviewing one concept (like “loops”) per class and then “setting them free” to work at their own pace, then circulating to observe and offer suggestions as they work. This is logistically challenging, but it doesn’t seem right to enforce the same group pace that we did when we started out.

Thanks for any experiences or input you can share!