Count back & use the relationship between addition and subtraction to subtract within 20. Warm up with a Mystery Math Mistake to find the error in DC's addition. Use ...

Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, ...

The common-core math standards require that students learn the standard algorithm for multi-digit adding and subtracting—you know, the process in which you line the numbers up vertically to add or ...

Solve word problems using a checklist. Engage in a Number Talk to find "how many." Solve addition and subtraction word problems with a Step-by-Step Visual Model checklist. Understand what the problem ...