True Scale Multiplication Grid

An innovative true-to-scale multiplication table has been developed by a UK math teacher who blogs at on Twitter @TheChalkface.

The cool thing about the multiplication grid is that each value is represented by a size-true number of squares. So 1 x 5 is represented by 1 row of 5 boxes. And 5 x 1 is represented by one stacked pile of 5 boxes. Perfect squares are, well, square!

Here’s the Original Coke True Scale Multiplication Grid

Compare this design with


May 1, 2017 at 11:59 pm Leave a comment


I really, really like this estimation problem.

The bag tells you the total number of ounces of candy.

That gives you some perspective.

I can adapt this for my 6th graders in

(1) having them predict
(2) then after the answer video discussing why their prediction was accurate/inaccurate
(3) ask if their predictions could have been made more reasonably and not just a guess
(4) ask them to determine the weight of each candy bar (using the package info)
(5) predict the number of bars that make up a pound
(6) take a standard Snickers bar and ask them to determine precisely how many minis make up a standard Snickers

When Math Happens

How many Snickers are in the bag?


Video Answer

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April 11, 2017 at 2:01 pm Leave a comment

Flags of Mathland

February 22, 2017 at 9:58 am Leave a comment

Edison Lee Does Percent!

One of my favorite cartoons is “The Brilliant Mind of Edison Lee”

In today’s newspaper, there’s a great Edison Lee cartoon, and it’s tapping into the fear generated by the new Executive and his administration. And I developed it into a problem for my 6th graders.

Here goes:

According to one source, if you were to dig and build a storm or bomb shelter in the basement of a 1 family home, it would cost between $5,000 and $6,000.
If you could use the 25% savings that Edison Lee found in the newspaper, what would be the range in prices of a storm or bomb shelter?
Show all work and explain your thinking clearly!

February 1, 2017 at 2:25 am Leave a comment

The Student-to-Teacher Dictionary

Math with Bad Drawings

Sometimes students say precisely what they meant. “I don’t understand the question” means they don’t understand the question. “This is too hard” means it’s really too hard.

But sometimes, it takes a little translating…20161024085458_00043

Half of my classroom conversations go like this.

Student: “I don’t get the question.”
Me: [longwinded, exhaustive explanation of what the question is asking]
Student: “Yeah, I knew that. But I don’t get the question.
Me: “Oh. This is one of those conversations.”

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October 26, 2016 at 10:51 am Leave a comment

30-60-90 Triangle Theorem

Motion graphics were created by Mac Square. How do you make sense of the 30°-60°-90° triangle theorem? What activities or resources have you used with your students to investigate the why?

Source: 30-60-90 Triangle Theorem

October 4, 2016 at 8:57 pm Leave a comment

Why Not to Trust Statistics

July 13, 2016 at 8:54 am Leave a comment

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