Max Rescues Runaway Horses: Subtraction Sprint!

About this Grade 1 Subtraction Within 20 Drill

Subtraction within 20 is a cornerstone skill that helps six- and seven-year-olds develop number sense and mental flexibility. At this age, children are building the foundation for all future math reasoning, and subtraction teaches them that numbers can be broken apart and recombined. When your child subtracts 7 from 15, they're not just following a rule—they're learning how quantities relate to each other and gaining confidence with numbers they'll see every day. This skill shows up naturally in childhood: sharing toys, figuring out how many cookies are left, or counting down during games. Mastering subtraction within 20 also strengthens their ability to count backward, recognize number patterns, and solve simple word problems. These early successes build the mental math habits that make arithmetic feel manageable rather than overwhelming as math grows more complex.

What your student will practice

• Solve subtraction problems with numbers 0 through 20 fluently
• Use counting backward and number line strategies to find differences
• Represent subtraction using objects, drawings, and written equations
• Apply subtraction to solve simple real-world problems and word scenarios

Common mistakes to watch for

Many first graders count incorrectly when finding differences, especially when they try to count on their fingers without a clear system—they might recount a number or skip one entirely. Another common error is confusing which number is being taken away; a child might read 13 − 5 as "take away 13" instead of "take away 5." Some students also struggle with problems where the answer requires crossing 10 (like 16 − 8), and they'll guess rather than use a strategy. Watch for a child who counts very slowly on every problem, hesitates on the same facts repeatedly, or gives answers that are way too large or small—these signal the need for more concrete practice with objects or drawings before moving to symbols alone.