Slippery Snail

Why play this game?
This game offers a motivating context in which children can improve their logical thinking skills.  It is a low threshold high ceiling game that is easily accessible but, at the highest level, has the potential to be generalised.

Possible approach
To start with, invite the children to play the game several times in pairs to get used to how it works. Students can either use the interactivity or a game board and four counters (available as a word or pdf document). You may notice some of them start looking for a way to win, so use a mini-plenary to discuss this as a class. Together, play against the computer - what strategy is it using? Why? At what point do pupils realise they are going to win/lose the game?

Encourage the children to record their moves and help them to articulate their ideas about strategy with sentences such as, 'I noticed that when I ..., xxxx happened'. Encourage them to think more than one step ahead: 'If I do this, then xxxx may happen and then I can xxxx. This would be useful because ...'.

Also encourage the children to articulate a hypothesis of 'how to win' and to try out their hypothesis a number of times. If it fails, they need to develop a new hypothesis. Children who think they have different winning strategies could play against each other and see what happens, taking it in turns to go first. Opponents will soon become partners in investigation as they test their hypotheses. Children may like to try out their winning strategy at home or at playtime.

Encourage them to think abut how they can record their winning strategy, maybe in the form of 'Top Tips'.

Key questions
What happens when there is one counter left? What about when there are two counters left?
Does it matter who goes first? Why or why not?

Possible extension
You can encourage the children to think about 'What if ”¦?' questions, such as:
What happens if you start the game with a different number of counters?
What happens if the counters start in different places?
What happens if there are more or fewer spots to start with?
Each time the conditions change, encourage children to adapt their winning strategy to fit the new conditions.

Possible support
You could offer to record a game for children who are struggling. You can then look back together at key moments. This might enable you to discuss what each player could have done differently at certain points in the game. Look closely at how the computer plays - can we work out what the computer's strategy is? Why is this a good idea? Can pupils work out a winning strategy based on how the computer plays?

You might want to adapt the game so that there are fewer spots/counters to begin with. If there are two counters, what would a good strategy be?