How it works
The tablet lies flat and a child sits at each end. The top half of the screen is
turned through 180 degrees, so each of them reads their own half the right way up.
The same question appears on both halves. First correct answer takes the point, and
first to five wins. A wrong answer costs that player the rest of the question but never
a point — taking points off a child who is already losing ends the game in tears.
Four levels: adding and taking away inside twenty, then inside a hundred, then the
times tables, then all four operations at once.