We are wholly inspired by Bret's work, and are currently playing around with the tangle library to help students visualize the concept of area, perimeter, and volume. Here is a preview: http://tuvalabs.com/resources/area/
We also plan to open source this code in due time. Ignore the mess please.
A suggestion for the visual area widget: Count the boxes for the user. So in the first box you'd write 1, the second 2, etc. Then it's easy to verify that the numbers are indeed a counting (they increase by 1) and that the calculated are indeed checks out.
I'd write the numbers in gray so they don't dominate the image.
Thanks for the feedback. There is a lot of work that still needs to be done to improve the UI for these tools, but our goal is to build a library of such visual tools for tens of relevant topics.
I share your passion for revolutionizing math education, but I don't quite understand the attachment to "Common Core." Federal prescriptive nonsense is a huge obstacle for real innovation in education and outside of the need to make a sale I don't see why you'd limit yourselves.
personally, I feel uncomfortable reading stuff like "If the width is 2 units and the height is 2 units, the area is 4 square units since 2 times 2 is 4".
2 plus 2 is 4 as well, yeah ?
As also, 2 ^ 2 = 4
The area is 4 regardless of what 2 times 2 is, or 2 plus 2 is, or 2 raised to 2.
I get your intent, but the phrasing is questionable pedagogy at best.
They'd be quite small touch targets assuming you wanted to view the shape and calculation as you change them. Have you considered making the shapes resizable by dragging?
We also plan to open source this code in due time. Ignore the mess please.