Systems of Linear Inequalities Game on Desmos

This game needs a name yet.  Your help is appreciated with that endeavor.

First I'll tell you how we played it in class, then I let you know what the students suggested, and finally I'll tell you want changes I think I'll try next time.

Initial Rules

Break the class into 5 teams.  I use 5 teams because desmos has 5 colors other than black (purple, blue, red, green, and orange).

Each team starts with 1 trailer (ordered pair): (0, 2) (0, 3) (0, 4) (0, 5) and (0, 6).  Each a different color.  

The inequalities y < 1/1 x + 0 and y > -1/1x + 0 are the two inequalities.

The overlapping shaded region is the area that is safe from tornadoes, so the players will want to move their trailers there or actually move the shaded region.

Each team rolls a die to see what they can do:

1) Change one of the slopes to whatever they want
2) Change one of the y-intercepts to whatever they want
3) Change the direction of one of the inequalities
4) Move a trailer to where ever they want (must be visible on the screen)
5) Get another trailer
6) Unleash a tornado. 

To unleash a tornado, I numbered each region of the graph that was created by the inequalities, except the overlapping shaded region, then rolled the die.  So if the regions were labeled 1, 2, and 3, and I rolled a 2, all the trailers in the region labeled '2' would be deleted.  If I rolled a 4, 5, or 6 then the tornado never formed.  

We played this for the entire period (45 minutes), and the team with the most trailers by the end of the class was the winner.  I had two teams win with 3 trailers each.

The Students' Suggestions

There should be more ways to unleash tornadoes.
We should start with 2 trailers.

What I Will Try Next Time:

Instead of rolling 1 die, each team will roll 2 and then decide which they want to use.  I think I will still begin the game the same way, but because there are two dice and more options, the players will have the opportunity to add more trailers and unleash more tornadoes.  

What I Loved About The Game:

Students were practicing skills they normally hate.  Such as:

Determining if an ordered pair is a solution to a system of inequalities.  We had great discussions about trailers being safe from tornadoes or not based on where they were located.  They asked if it was safe to be on the dotted line.  They asked if it was safe to be in any shaded region or just where they overlap.  

The students discussed what would happen if they changed the direction of the inequality in one equation as opposed to the other.  Would their other trailer be safe?  Where would the overlapping be?

They debated about how to change the y-intercept or the slope to make one of their trailers safe but not one of their opponent's.  

I can't get these discussions when I hand out worksheets, but tornadoes sweeping away their mobile homes, they're all over that.

Here's what our 'game board' looked like at the end of class:

Thoughts?  Comments?  What about a title for this?

*UPDATE* 3/29/2014

I played this game with a different class and we tried the following rules and it made the game more exciting.

1) Roll two dice, allow the students to determine which number they want to use.  If a 6 is rolled, a tornado must be started.  

2) When a 6 is rolled:  Number the unshaded regions so that all numbers 1-6 are used.  So if there are three unshaded regions label them 1&4, 2&5, and 3&6.  This way a tornado always forms.  

We also discussed ways to damage your opponents mobile home.  Perhaps there could be a way to steal their tires so they can't drive to another location.  

Have any of you played this game?  Any feedback for me (good or bad)?


  1. Love the idea! I'll be doing systems in a few weeks with my kiddos, I'm pinning this idea for then. Here in Maine we don't see many (any) tornadoes, but I think they'll get into it anyway. You could also unleash typhoons, forest fires, a swarm of locusts, boils, zombies... I might just call it "Flatten Your Neighbor" and appeal to their gruesome sides :-)

  2. Hello,
    Starting inequalities and am going to use this but I need to clarify one thing..
    Once the students roll the dice do you take it in turns to change the graph (ie for one roll are you making 5 changes? or is it one team rolls, makes changes and then the next team rolls and makes their changes and so on?)

    thanks Christine

  3. @ Christine. I have one team roll, make changes, and then the next team rolls and makes their changes.

  4. Looking forward to doing this tomorrow!

  5. I used this game for the first day after winter break to get our brains back in gear without too much pressure. The kids loved it, and like your class, we had some excellent discussions about solutions to systems of inequalities. If they rolled a 4, they were allowed them to move either their own or another team's trailer, which added some action. Thanks for sharing this excellent idea!

  6. do you think this game would work as well if they were in pairs instead of teams?

    1. Since this is a turn-based game, there is a lot of down time for teams between each turn they have. If your students are well behaved or have something to do in the mean time, it should work.

      The other issue is the number of colors available on desmos, if you are using desmos. They only have 5 colors, and black.

      If you try it with pairs, please let us know how it goes.

  7. How are tve numbers labeled on tve graph

  8. How are tve numbers labeled on tve graph

  9. What a great game. I will need to come up with another theme, being that a week ago, we had a tornado come within 15 miles of our town. (Dallas area)... maybe something along the Star Wars lines?

    1. I live in Ohio where tornadoes struck big last year - so we play "Unleash the Kraken" and used boats instead of trailers.

  10. I played this game again, having seen it last year. What a hoot! I like playing it as you first describe, then asking what modifications we should use the next day. What a hoot!

    1. I guess I REALLY felt the game was a hoot. Not to self: edit.

  11. Hi! Loved this, but one question: when you number the areas, how did you decide what numbers in what areas? Did you do it before the students rolled? After? Or did you just do it at the beginning and those numbers stayed there the whole time?
    We did a trial run today and that was the area we were confused about.

    1. I just write the numbers in any order, then the students roll the dice.

    2. I'm trying this today:) We live in a tornado zone, so we are using the Kraken one. My question is like Tina's: do the numbers stay with the region or do they move as the slopes/y-ints/signs are changed. i.e. if you said 3rd quadrant is area 3? Or is area 3 one of the areas only shaded once which moves as the students make changes? (I'm not sure if I'm asking this clearly)

      So far, the students are liking it!
      Thank you:)

  12. This was really fun for my students and for me. Since we live in California, we used houses and earthquake epicenters. The kids added some competitive rules like being able to move any team's house if they rolled a 4. Maybe this was always the intent, but it did add some interesting twists. Thanks so much for creating and sharing!!

  13. Great Idea. I can't shake the notion that this is a lot like a weird version of battleship. I will follow all the team games ideas and edits, but then I may have teams compete against each other like battleship. I'll let you know how it works in September.

  14. Name for the game: "Tornado in a Trailer Park" definitely!

  15. Sounds like fun! I am ready to start systems of inequalities in class and will definitely try this. You could call the game "Twister". It's short and easy to say.


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