This is part of Wordless Wednesday…



This is part of the Teaching Math with Picture Books series.
Check out this activity you can do with What’s Your Angle Pythagoras?
Will you do it? What else can you do? Tell us in the comments.
And share this on Twitter!



I’ve been playing with the lovely Cuisenaire Rods for a few weeks now. I made the (fortunate) mistake of creating this flower in a past article about coordinate pairs.
The mistake was that I would eventually have to come up with the coordinates for this thing. Fortunate because it gives the MathFourTicians out there something else to teach with the rods!
Since all the “petals” are attached to the center, that’s probably the best place to begin.

Since everything is tiny (1 cm), I went to a bigger setup. And some of the coordinates were easy to pick out. So I put those in the big grid, too:

Next I considered what I was really dealing with: a square. And each side was 1 cm.
According to those crazy Pythagoreans, the diagonal measures :

So half the diagonal is :

When I put this information on the big grid, it looks like this:

Doing some arithmetic and geometry, I get:

Using my very cool TI-30 calculator, I get that .
Knowing that each corner pokes out roughly 0.2, I can calculate the coordinates:

From this I can create the ordered quadruples as described here for the petals of the flower. But at this point I’m pretty much needing a break. So I’ll leave that for next time.
Whatcha think? Fun? Share your thoughts in the comments and on Twitter:


This morning Daughter and I went to the gym.
When we crossed the street, I exposed her to undo risk by crossing at an angle.
So on our way out, I explained to her that we were walking a little further to get to the car this time. And we would minimize the risk of getting hit by a car by taking the longer route.
(Of course she’s not yet two, so she really didn’t care. But it was important for me to say.)
People most often cross the street at an angle. Intuitively we know it’s shorter. Look at the tiny person in this picture. He needs to get to the front door of the store.

Suppose walking one yard takes 5 seconds. It will take the little guy 15 seconds to cross the street straight across. (And with a toddler, it does take 5 seconds to walk a yard.)
Then he has to walk the four yards along the side to the door. Which means his total time is
3 yards across at 5 seconds per yard = 15 seconds
4 yards up at 5 seconds per yard = 20 seconds
Total walking time = 35 seconds
If he went at an angle, it’s 5 yards total (by the Pythagorean Theorem).
5 yards diagonally at 5 seconds per yard = 25 seconds
Total walking time = 25 seconds!
For the pedestrian in a hurry (and wearing the shirt that reads “Safety Third”) the angled route is the way to go. But for a parent with toddler in tow, minimizing risk is a better option.
If the little guy were to cross at the angle, he’d be in front of the oncoming cars for 25 seconds. If he were to take the route that is longer overall, he’d be in front of oncoming traffic for only 15 seconds.

Getting out of the driving area faster means keeping the driver happy. That might not be your goal, but adding some cosmic happy juice into the world of drivers never hurts.
Plus, if someone were to “hypotenuse you” by taking the angled route when you were driving, wouldn’t you get a little annoyed?
So be safe. And tell your children why.
It’s all about the math!
Share your thoughts in the comments.
