Common Core 1st Grade Math: Addition and Subtraction Equations

Gr 1–2—Using carnival games and attractions as examples, host Kristin Morris briefly introduces viewers to the principles of writing addition and subtraction equations. She clarifies that just as we construct sentences from words, mathematicians use symbols to construct number sentences, also known as equations. Three important symbols—the plus, minus, and equal signs—are introduced with corresponding hand motions to help viewers remember their meaning and function. "Thinking job" problems present corresponding math and word problems to viewers, but only a few seconds are given before the answer appears. A seemingly big conceptual jump is made between playing a true or false game—to determine if addition equations are correct—and the "What Is the Commutative Property of Addition?" section. The commutative and associative properties of addition for adding multiple numbers are also discussed, and a final "challenge question" is presented for which no answer is given. The video assumes that viewers have some knowledge of math strategies, as the terms mental math (making calculations in one's mind without writing notes or using a calculator) and count on strategy (starting with the highest addend in the equation and counting on the smaller addend) are used and implemented without prior explanation.