Tuesday, March 3, 2015

Examing a graph and 35 game (math class 12)

Who: Baan Pathomtham 1st and 2nd grade classes
Where: In school
When: after science and before lunch

Weekend outing

Our school went to a play over the weekend, somewhat about chickens. Unfortunately, there were no mathematical chickens, but maybe someone will draw one this week?

Dice turn into a graph

The homework last week was to play damult dice with subtraction, targeting a score of exactly 100. We had discussed some observations about the game and had left open the observation that a lot of scores seemed to be multiples of 3. Over the week, I made a little pencilcode program to show the scoring distributions and thought this would be another good focus for the kids to make observations, conjectures, and pose questions. The distribution we discussed today was the max scores distribution, so you can play along here: Scoring histograms.

Once again, this turned into a good conversation:
  • Why are some bars red and some blue?
  • What is the meaning of the two rows of numbers on the bottom?
  • How does this relate to our dice game?
  • In the top row of numbers, why is 2 the smallest? Why is 72 the largest? Why is 3 missing?
For homework, we gave everyone a copy of the possible scores histogram and assigned them to write an observation or question about the graph.

35 Game

This is another card game. I'm not sure of the source, but will link back here when I find it.
Material: Pack of standard playing cards (J=11, Q=12, K=13), manipulatives for adding (we used 100 charts) are also helpful.
Set-up:Deal out all cards to the players. In the first version, it doesn't matter if people have different numbers of cards. Players don't look at their cards.
Play:Going clock-wise around the table, the player turns over one card and adds its value to the running total, if that result is less than 35. If the sum is 35, the player scores a point and the running total resets to 0. If the sum would be more than 35, then the player subtracts the value of their card from the total instead of adding.
Example: if we have gotten to a total of 26 and the next player puts down a 9, they would get a point. If they turn over a 10 or face card, then they subtract that value from 26.
  • When the card value is too large, encourage the kids to state the addition equation anyway. For example, "30+10 = 40"
  • Before playing a card, ask what value would take you to 35.
  • Occasionally ask for values larger than 13 and ask if there is a card that would let you get to 35 on the next play.
  • For a more involved version, deal equal numbers of cards and let player's choose which card to play on their turn.


  1. Write down at least one observation about the damult dice possible scores histogram
  2. Play the 35 game with a parent or sibling until someone gets to 5 points and wins

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