Phillip: thank's for the comments. Yesterday I changed the format a bit. After we did the warm up I did some basic footwork (Irimi-tenkan-twist your body all the way and get down on one knee). We don't usually do this type of training in our dojo, as we expect it to develop from understanding of the waza, but it is a great way to make it simple for the kids.
We did the drill for 4-5 minutes (I build it up gradually - first one step, repeat - then two steps, repeat and finally the whole deal). Afterwards they did two techniques that have the same pattern for footwork. I think it worked very well for them. Techniques were aihanmi katatetori ikkyo ura and aihanmi katatetori shihonage ura.
Now I will try to find a similar pattern for next weeks practice
Mary: please let us know how what your experiences are