First Connect Three

'First Connect Three' printed from https://nrich.maths.org/

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First Connect Three

In this game the winner is the first to complete a row of three, either horizontally, vertically or diagonally.

Spin the spinner, place each number in one of the squares and decide whether you want to add or subtract to produce a total shown on the board. Your total will then be covered with a counter.

You cannot cover a number which has already been covered.
If you are unable to find a total which has not been covered you must Pass.

You can use the interactive version below or use two 1-6 dice to play away from the computer.

Are there some numbers that we should be aiming for? Why?

Which number on the grid is the easiest to get? Why?

Which number is the most difficult to get? Why?

Printable NRICH Roadshow resources: Instructions and Game board.

For a more challenging version of this game, you could look at Playing Connect Three, and/or change the settings of the interactivity by clicking on the purple cog.

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Why do this problem?

This problem is a great way for students to take responsibility for their own learning. They can avoid negative numbers if they are not confident or they can push themselves to calculate negative answers. In analysing the game more fully, rather than just playing it, the idea is that learners can develop a system for finding all the possible ways of making each number on the grid, so they can justify which are the easiest to get.

Possible approach

This printable worksheet may be useful: First Connect Three.

You could introduce the game by playing against the class, or by splitting the class into two teams to play against each other, or with the class playing against the computer. Students can play against each other in pairs to get more of an idea of the game. You can print off this board if the students are not playing at a computer or laptop and use dice instead of the interactive spinners.

After a suitable length of time, ask the suggested questions in a whole-class discussion that focuses on emerging strategies, observations, explanations and justifications. Students can then go back to working in pairs to establish the numbers of ways of achieving the different totals.

At the end of the lesson a plenary discussion can offer a chance to present findings and you can draw attention to those methods which were particularly efficient. This would then lead to a discussion about how their findings might affect the way they play the game to win.

Key questions

Are there some numbers that we should be aiming for? Why?

Which numbers on the grid are the easiest to get? Why?

Which numbers are most difficult to get? Why?

Possible extension

Further challenges could be provided by asking what would happen if:

there was a differently shaped board
numbers appeared more than once on the board and you could place more than one counter in a turn
you could use 1-12 spinners (or dice)
you wanted to design a board for a game where you allowed multiplication and division

For students who are able to add and subtract both positive and negative numbers, Connect Three is a suitable extension.

Possible support

If some pupils are struggling, you could adapt the board so that it only contains the numbers 1-12. You could also suggest pupils play in groups of four, one pair against another, in order to support each other while carrying out calculations.