Starting a new academic year brings both new challenges and new resources. I'd like to share a resource from the LINCS collection. Interactivate is a set of free web-based resources for Math and Science instruction focused on modeling. There are 187 math lessons, but the lessons on modeling are particularly recommended for adult education classes.
I invite you to check out this resource. Have you used this in the past? If so, how did it work for you/? If you look through this, consider sharing how you would use it with your students.
I used something from shodor in the past -- don't remember what it was, but I remember being impressed with it :)
Looking at the list now, I thought "these are 'way above what we're doing," but I kept scrolling and there are lessons for more basic things. http://shodor.org/interactivate/activities/AreaExplorer/ is a cool "area explorer." Now, the questions that go with it -- for grades 3-5? - are complex text and jump straight to the abstract generalities. Students who are "exploring" would benefit from a little more guidance, I suspect. What's a "grid line intersection" anyway? A corner? No, I think we're counting lines -- essentially counting out the perimeter... so asking "what's the correlation" .. it just feels uncomfortable. Still, I could see using this and having students have directions for filling in the "record sheet" and facilitating discovering the different shapes with same perimeter and different areas...