One thing that I came across recently on the NRICH math website is an quick primary students’ game for practicing addition and subtraction with numbers to 20. On the particular webpage for **“Strike it Out”**, they offer a **poster** (a picture of which is posted here), a **short video clip** of the game, and a **power point file** all which give the instructions for the game.

I had each of my grade two math classes playing this game recently as a warm-up activity, and they loved it! The games go quickly for the most part – of course, some of the pairs of students were slower at the game, but those students were still engaged and trying their best.

**The rules, simply, are these:**

• Using a number line marked 0-20, one student begins by creating and recording an addition or subtraction equation, e.g., 4 + 10 = 14. On the number line he crosses out the 4 and 10 and circles the 14. His turn is over.

• The partner must now create a new addition or subtraction equation, but it must use the number 14 as one of the first two numbers, e.g., 14 – 6 = 8. She would crosses out the circled 14, crosses out the 6, and circles the 8. Her turn is over.

• The 8 must be used now by the first partner in his new equation, with the recording and crossing out and circling continuing.

• Play continues until one of the partners cannot make a correct number sentence, and the player who made the last correct equation wins.

Although there are many possibilities for equations near the beginning of the game, there are **fewer possibilities as the game progresses**. I watched students doing a lot of mental math trying to come up with appropriate equations. The **students who needed support had a set of ten frames on the table to use to help the visualize and calculate.**

I am including for download the game board page I made for students to use. (Cut the page in half to use.) Two students play on a single game board at a time.

There are lots of other great ideas on the NRICH math site for many different levels. I hope you will take some time and explore what is there!

Mathematically yours,

Carollee

Link to game on the NRICH math site here

Download the game board here.

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