1.OA.D.8 Grade 1 · Operations and Algebraic ThinkingDetermine the unknown whole number in an addition or subtraction equation relating three whole numbers.Common Core State Standards for Mathematics, as adopted in the Massachusetts Curriculum Framework for Mathematics (2017), Grade 1.
Play the game: ClimbSteps 39–43 of the ColorMyMath curriculum · free, no sign-up →Addition is a length — dots laid end to end on the number line. Taking away comes down the same line. Every fact is shown as a picture before it is ever asked for from memory.
Every page is free and open — nothing to install, no account, and it works on a phone or a classroom board. Every number has its own color: 1 red, 2 orange, 3 yellow, 4 green, 5 blue, 6 purple, 7 brown, 8 pink, 9 cyan, and a number is that many colored dots.
Step 39Climb: 12-3=9, 11-2=9Step 40Climb: 12-4=8, 14-5=9, 11-3=8, 13-4=9Step 41Climb: 11-5=6, 13-6=7, 15-7=8, 17-8=9Step 42Climb: 12-5=7, 14-6=8, 16-7=9Step 43Climb: 11-4=7, 13-5=8, 15-6=91.OA.A.1Word problems within 20: adding to, taking from, putting together, comparing, with the unknown anywhere1.OA.A.2Word problems with three numbers that add to 20 or less1.OA.B.3Use properties of operations to add (3 + 8 = 8 + 3; 2 + 6 + 4 = 2 + 10)1.OA.B.4Subtraction is an unknown-addend problem (10 - 8: what goes with 8 to make 10?)1.OA.C.5Relate counting to adding and subtracting (count on 2 to add 2)1.OA.C.6Add and subtract within 20: counting on, making ten, breaking down to a ten, doubles; fluent within 101.OA.D.7The equal sign: decide whether an equation is true or falseColorMyMath · getridoftheteacher.com · every number has its own color, and a number is that many colored dots. Matching a game to a standard is a judgement call; the official text is at doe.mass.edu.