Substitution activity Harder Algebra

The activity is a substitution tournament. Students generate values to substitute into algebraic expressions. The expression which repeatedly has the highest value is the winner.
I found the substitution tournament useful for encouraging students to practise substituting values into an algebraic expression.
The game works well when it is played in pairs.
The game aspect encourages the students to talk about the process of substitution and to make decisions.
Before the students begin playing, I usually ask them to look at the expressions and put a mark next to the one they think will win. This can generate a good discussion after the game has finished.
Extension: Give the students 2 different coloured dice. Tell them that one colour is positive, the other is negative.
Extension: Give students a 10 sided, 0 to 9, die.