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 ...

Students put all of their addition and subtraction skills together to solve equations. In this lesson, students put all of their addition and subtraction skills together to solve equations. Julia ...

Susan Hobart asked this week’s “question-of-the-week": What strategies help math facts stick besides the old “drill the skill” and, if someone is not proficient at addition facts, can learning ...

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, ...