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This Subtraction Within 20 drill has 40 problems for Grade 1. Farm Animals theme. Answer key included.
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Max discovered lost baby animals scattered across the farm—he must reunite them with mothers before sunset!
Standard: CCSS.MATH.1.OA.C.6
Preview
Page 1 — Drill
Page 2 — Answer Key
What's Included
About this Grade 1 Subtraction Within 20 Drill
Subtraction within 20 is a cornerstone skill that helps first graders move beyond counting on their fingers and develop true number sense. At ages 6-7, children's brains are ready to internalize that subtraction is the inverse of addition—a critical insight for all future math. When your child can quickly solve problems like 15 - 3 or 18 - 5, they're building automaticity that frees up mental energy for word problems and real-world scenarios. Whether removing items from a pile of farm animal toys or figuring out how many cookies are left after sharing, subtraction within 20 appears constantly in daily life. Fluency with these facts also strengthens working memory and helps children recognize patterns in numbers, laying a solid foundation for two-digit subtraction and beyond.
What your student will practice
- Solve subtraction problems with minuends up to 20 with accuracy
- Use counting back and number line strategies to find differences
- Recognize the relationship between subtraction and addition facts
- Apply subtraction reasoning to simple word problem contexts
Common mistakes to watch for
Many first graders confuse the order of numbers in subtraction, computing 7 - 12 as if it were 12 - 7. Others rely too heavily on finger counting and lose track midway, arriving at incorrect answers. A third common error is misreading the minus sign as a plus sign, especially when problems are presented in mixed formats. Watch for students who count the starting number instead of starting their count at the next number—for instance, counting "7, 8, 9" when solving 9 - 2 instead of starting at 7. These patterns often signal the student needs more visual supports like number lines or tens frames.
Create a simple subtraction game using household objects or toys—even farm animal figurines work perfectly. Place 15 small items in a row, call out a subtraction fact (like "17 take away 4"), and have your child physically remove that many items, then count what remains. This concrete, hands-on approach helps solidify the concept that subtraction means "taking away," and the repetition builds fluency naturally through play rather than drill. Rotate who gives the problems so your child stays engaged and develops ownership of their learning.