Popcorn Pandemonium


Download the videos, images, and resources by clicking download below

My afternoon grade 9 applied class (as a group) is very outspoken, loud, and restless (maybe it’s because it’s the afternoon and they have been sitting at desks all day). They have been a challenge to keep on task. So….I  am trying to find opportunities for them to be outspoken, loud, and restless.

A few weeks ago I came across this post by John Berray. Using/eating marshmallows to compare rates of change. I loved his idea of “experiencing rate of change” I decided to re-purpose his lesson to meet our goal of—> “I can solve a linear systems of equations by graphing.” I also took his recommendation of using popcorn instead of marshmallows…..and it paid off!!

Here is the low down…. we start the “Math Dial” off low.

ME: OK you are going to have a good o’ fashion popcorn eating contest!

Start with this video:

Ask for questions:

Here are a few from math tweeps

here are a few questions we can address with this problem.

  • When will Tim and Don eat the same amount as Jon?
  • Who will eat the most when the minute is up?
  • Will there be a time when Tim and Don eat the exact same amount?
  • When would Don eat more than Tim?

ME: Ok lets figure out who will eat the most in the 1 minute. But I want to recreate the video with you guys.

So I made a giant bowl of popcorn. (Don’t have time to make enough popcorn? — have kids give high fives to a timer instead)

Arrange groups of 2 or 3 and everybody grabbed some popcorn to start!

Round 1:

In each group kids are to choose who to mimic, Jon, Tim, or Don. They are to eat just like them! Allow them to ask about how fast each person is eating….or how much did each start with, etc.

Show Act 2 to answer those questions:

Tell them to get their timers ready….because they will eat just like one of those guys. Ready…..all you Tims and Jons eat your starting amount … Set….Go!

Start the timers and eat!

Question 1:
After they are finished, have them work out on their whiteboards who would eat the most in a minute.

Question 2:
When would Tim & Don eat the same as Jon if ever? (Great potential here for integer solutions talk).

Question 3:
During the minute, at anytime did Tim and Don eat the same?

If there was no time limit find when Tim & Don would eat the same?

Used this handout so they could create tables of values. Had them graph in Desmos!

Screen Shot 2014-12-04 at 7.33.08 PM

The awesome thing was that my students were desperately trying to find the equations to match their graphs….they didn’t want to plot all the points. I visited each group helping them find the equations if needed. Once the equations were in desmos they knew where to look.

Screen Shot 2014-12-04 at 7.54.39 PM

Act 3 – The reveal of who ate the most in a minute

Round 2: Do it all over again with new eating patterns!
Here are two possible eating pattern cards to give out:

Screen Shot 2014-12-04 at 7.31.27 PM Screen Shot 2014-12-04 at 7.31.45 PM

Students who finished early worked on our Crazy Taxi  vs. a new Insane Cab

Screen Shot 2014-12-04 at 7.33.26 PM

(@mathletepearce has a nice write up on using the Crazy taxi problem in class.)

Next day! Solving Multi-step equations…..will solve this systems of equations algebraically.


Download the videos, images, and resources by clicking download below

Water Balloon Mishap!

Another 3-Act Math Problem.

I originally created this problem for the iBook I made for Linear Relations. I used the problem with grade 9 academics on the first day of school this year to get them introduced to the 3-Act style of questions.

This problem also has worked well with a grade 9 applied class when working with ratios and rates.

Here’s the problem,


Ask students: What were your “Wonder Questions” – What did you wonder?

Students will most likely ask when will the balloon explode, or how much water is in the balloon.

Ask Students: What information would you need to know?



Teacher Note: When I did this problem with students I was interested in applying rates, so when students wanted to know how big the balloon would get I told them the standard balloon will hold 14 Litres of water. If I was doing this near the end of the course I would tie in the volume of a sphere [Most balloons will have about 12 inch diameter.]



iPhone Charger

Use this problem based task to generate a need to graph relationships, analyze linear relations, and extrapolation.

Act 1- Video

When will the phone charge?
1. Give an answer that is too high.
2. Give an answer that is too low.
3. Find how long it will take to charge.

Act 2 – hints
1. Make a table of values comparing the time and the percentage.
2. Graph the relation.
3. Find an equation to model this relation.

Act 3 – Video

1. What could cause the difference in answers?