There are 2 sides per coin, and 3 flips, so 2^3 = 8 total items in the sample space
HHH
HHT
HTH
THH
HTT
THT
TTH
TTT
Tracing each branch from left to right will help form the 8 different outcomes. For instance, if you go along the upper most path of the upper tree, then you'll get HHH meaning you got 3 heads in a row. The next branch down would be HHT, and so on.
