River Crossing Jr. uses a solution code, written as a series of plank or Cat movements between stumps. Each stump has an assigned number or letter.

The first two letters / numbers indicate the location of a plank and the second two letters/ numbers indicate where to move it. For example, if the code reads 2F-FH, move the plank located between stumps labeled 2 and F to F and H.

In Challenges 6-10, if the code reads L-3, that means move the Cat from stump L to stump 3.