Tuesday, December 16, 2014

Math games 7

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

Skip counting warm-up

We've talked about warm-ups in several previous posts. Today, it proved to be a more substantial discussion than expected for a warm-up.

For skip counting, we go around the room with each child saying the next number in the sequence. This time, we started with some easy skip counting (2 and 3, based on requests of the kids in the class) and then something a bit more difficult (6 or 7).

Along the way, we saw some people getting stuck and knew that they would benefit from seeing some new strategies. When one child appeared to do a calculation very quickly, we asked them to explain their thinking. It turned out to involve splitting and regrouping:

We asked why they decided to split 6 into 4 + 2 and this was the explanation:

This discussion happened in each class and, in each class, we gave it the name of the student who explained it (Minnie and Jiping). For the rest of the day, when someone got stuck, their friends would offer encouragement and say "try X's method."

By the end of this warm-up, the second graders were excited enough that wanted to show off their technique for multiples of 9, so they spontaneously launched into that.

Parents at home: you can do the skip-counting warm-up driving together or at a meal time. Ask your child to show you how to get started.

If they are having difficulty with a calculation, first give them time to think through it.  Next, suggest tools they can use: write it down on paper, draw a diagram, use some objects. Finally, ask if they can break it into pieces that they know.

Ring your neck

Since some kids weren't in class last week, we began our games with a review of the new game from last week. It was a bit messy in second grade, but in first grade we got them to take turns explaining rules (one child explained one rule) and then they split into two teams to play a demonstration round.

Our intention had been to discuss strategy for this game, but the group dynamics didn't work well. These are the types of leading questions that encourage them to think about the structure and strategy of the game:

  • Do you want to go first or second?
  • If there is only one card left, do you want it to be your turn or your opponent? What about 2 cards? What about 3 cards? What about 4 cards? ....
  • Is it "good" to take a card (do you expect to get points or lose points when you take a card)? What is the most points you could get? What is the least? What are all the possibilities?  What is the average?
  • Do these things change as the game is played?
Parents at home: when playing games with the kids, ask them to explain the rules. As they are explaining, encourage them to show examples.  When you are playing this game, encourage them to add up their score each time they choose cards. Be patient when they need to take time doing the calculations and use the suggestions above when they get stuck.  When they aren't stuck, ask them to explain how they were thinking.

Finally, ask them the strategy questions.  It can be a fun discussion, especially when you don't know the answers!

Strike it Out

Players: 2
Material: paper and pencil
Set-up: Draw a number line and tick for each whole number. We gave the kids printed pages with number lines up to 20, but you should feel free to make longer or shorter number lines.
Start of play: the first player chooses a number and circles it
Each round: using the latest circled number, the player chooses another unused number, and forms a number sentence where the result is a second unused number. Circle this result and cross out the other two numbers.
Winning: the last player with a legal move wins.

This is an NRICH game and these pages show examples: student page and teachers' note.

Parents at home: This appears to be a more complex game as there are so many choices at each step.  When there are a small number of choices left, ask them to predict whether they can win. Also, ask them how many ways there are to form the number sentence and whether it makes a difference.


  1. Play strike it out with parents, friends, and siblings
  2. Play at least one of the card games we have taught this term.


First, we had a lot of fun playing these games with the kids this term. I think we found a collection of games that were fun for the kids and reinforced mathematical concepts appropriate for their current understanding. When playing the games, the kids were focused and engaged. Also, at least one of these (ring your neck) also has potential as a more subtle strategy game, though you have to reduce the value of the final bonus card.
When we weren't playing the games, we often found it difficult to keep everyone together for a discussion. This is something we will discuss with the teachers and think about strategies for next term.

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