Revisiting Larry Guth’s “no rectangles” problem – one of the best math activities for kids I’ve seen

I was looking for a relatively stress-free project to do with the boys this morning and thought it would be a good day to review one of my all time favorite math projects for kids -> Larry Guth’s “no rectangles” problem. One of my all time favorite moments doing math with kids came when I used this problem for a 2nd and 3rd grade Family Math night at my younger son’s elementary school a few years ago. The problem is accessible to kids of all ages and also of interest to research mathematicians.

We started with a quick review (and lucky clarification!) of the problem and then the boys tackled the 3×3 case:



Next we moved on to the 4×4 case. The thought process the boys went through here I think shows why this is such a great math problem for kids to talk through:



Next I had a film goof up – luckly it was just 30 seconds of introducing the 5×5 case and telling them that answer to the 5×5 case was 12 squares. Don’t know what happened to this piece of the film, but since the plan was for the boys to play with this part off camera anyway I didn’t bother trying to fix it.

In any case, here’s the 12 square covering for the 5×5 they found and then a brief discussion about the surprise that comes when you move to the 6×6 square:

Again, this is one of my favorite math projects for kids – and kids of all ages. It is a really fun problem to play around with.

3 thoughts on “Revisiting Larry Guth’s “no rectangles” problem – one of the best math activities for kids I’ve seen

  1. Do you have a link to somewhere I could read about the 6×6 and NxN cases? I found Larry Guth’s lecture announcement, but I was unable to find an examination of the NxN problem.
    Thanks for the interesting problem to think about!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s