Two and One

Two children are playing a game with three balls, two blue ones and one red one.
Terry is red and Ali is blue.

They toss up the balls, which run down a slope so that they land in a row of three, like this:

The colour in the middle wins that round. Is this a fair game?
Who do you think will win?
Why?

Try using the interactivity below to get a feel for the game. (The sum column tells you how many times Terry has won so far.)