Solve one-step word problems using a visual model & a problem-solving process. Warm up with a Mystery Math Mistake to hunt for the mistake in adding two 2-digit numbers using a decomposition strategy.

One idle evening last October, Mehtaab Sawhney took up an old pastime. He began perusing the website erdosproblems.com, an updated record of the 1,179 conjectures left behind by the eccentric and ...