If you are working in a group, discuss first how the number line gets filled up and why we need more numbers than just the counting numbers. This question will be revisited in the next session.
Algebraic numbers also include some complex numbers (e.g., , the solutions to x2 + 1 = 0). Such numbers, however, are excluded from this activity and this session since they cannot be represented on the number line.
, the solutions to x2 + 1 = 0). Such numbers, however, are excluded from this activity and this session since they cannot be represented on the number line. 
