Why the strategy, not the algorithm, comes first

Practice mode flashes a problem and reveals the strategy in one animated pass, the same rhythm as Fact Fluency Strategy Flash. Model mode steps through that same sequence one click at a time, so you can pause on exactly the move a class needs to see. Every step carries its own narration line and discussion question, never just a shape moving across the screen.

Jump strategies, moving along the line in friendly chunks, hold up better than splitting a number into tens and ones and operating on each place separately, especially as problems get harder. That's why Split by Place Value only shows up under addition here: for subtraction, splitting by place value runs straight into the same regrouping trouble kids hit with the standard algorithm, just done in their heads instead of on paper. Compensation and Constant Difference are related but different moves: adjusting one number to something friendlier, versus shifting both numbers by the same amount so their difference never changes. Compensation typically develops first, with Constant Difference showing up later once kids trust that a difference stays fixed under an equal shift. Watch for two specific slips: with Compensation, kids adjust one number but forget to compensate back on the other side. With Constant Difference, the usual error is shifting only one of the two numbers instead of both.