Same difference

Mr Gregg held up two Cuisenaire rods and said, "can you find two other Cuisenaire rods with the same difference?"

Then, "can you find other pairs with the same difference?"

We thought there would be an infinite set of these, but here are some of the ones we made:

We talked about what written subtraction sentences these represent.
Samyak and Marie made a really good mathematical claim about these.

And there were plenty more things we noticed in 4B:

Just about all of us thought Marie and Samyak's claim was true, so afterwards we did some drawing and writing to explain why we thought so. Here's some examples:

... and a slideshow: