Great Classroom Action


Coral Connor’s students created 3D chalk charts to demonstrate their understanding of trig functions:

As a showcase entry we spent several lessons developing the Maths of perspective drawings of representations of comparisons between Australia and the mission countries- income, death rates, life expectancy etc, and finished by creating chalk drawings around the school for all to see.

Malke Rosenfeld assigned the Hundred-Face Challenge — make a face using Cuisenaire Rods that up to 100 — and you should really click through to her gallery of student work:

Some kids just made awesome faces. Me: “Hmmm…that looks like it’s more than 100. What are you going to do?” Kid: “I guess we’ll take off the hair.”

One of my favorite aspects of Bob Lochel’s statistics blogging is how cannily he turns his students into interesting data sets for their own analysis:

Both classes gave me strange looks. But with instructions to answer as best they could, the students played along and provided data. Did you note the subtle differences between the two question sets?

Jonathan Claydon shows us how to cobble together a document camera using nothing more than a top of the line Mac and iPad.

I'm Dan and this is my blog. I'm a former high school math teacher and current head of teaching at Desmos. He / him. More here.


  1. I’m intrigued by the 3D charts thing, but I don’t get much insight into how they were made. Is it something about setting the angles right? I need some more information.

  2. Thanks for sharing the C-Rod faces. A really great lesson to inspire number talk. Also I have to laugh at the cobbled together document camera for only $2,500 :) Last I checked IPEVOs were selling for $70 (well $100 if you want the extra stand)

  3. For years I’ve wondered how the size of SCHOOL X-ING, painted on the street, was determined to best be visible to cars as they approach it. Lots of variables. Was it just experimental then standardized or was a computation done to produce the best result.

  4. Hi Jonathan,
    The 3D chart thing shown above is a sample made my @markliddell and myself ( @cwoldhuis ) as a demo of how to create the 3D art. The creation of the art can be done a number of ways, this one was mostly measurement and perspective drawing, but later we used pythagoras and trig to determine actual lengths. See the video of the creation to see how we created it.
    Overall the students created about 15 different drawings depicting various forms of data – all focused on changing perspectives.
    Chris :-)