The Action of Subtraction (Math Is Categorical)
If You Were a Minus Sign (Math Fun)
Elevator Magic, Level 2 (MathStart Subtracting) (MathStart 2)
Monster Musical Chairs (MathStart 1)
Ten Sly Piranhas
Animals on Board (MathStart 2)
If You Were a Plus Sign (Math Fun)
Tally O'Malley (MathStart 2)
The Mission of Addition (Math Is Categorical)