Free printable math drill — download and print instantly
This Subtraction Within 20 drill has 40 problems for Grade 1. Explorers theme. Answer key included.
⬇ Download Free Math DrillGet new free worksheets every week.
All worksheets checked by our AI verification system. No wrong answers — guaranteed.
Max discovers five explorers trapped in the jungle! He must solve subtraction problems to find the secret rescue path before dark.
Standard: CCSS.MATH.1.OA.C.6
Subtraction-within-20 is a foundational skill that helps six- and seven-year-olds understand how numbers work together and apart. At this age, children are developing mental math strategies and moving beyond counting on their fingers—skills they'll rely on for multiplication, division, and algebra later. When your child can fluently subtract numbers like 15 - 3 or 18 - 7, they're building number sense and confidence with quantities they encounter every day: sharing snacks with friends, figuring out how many toys are left after giving some away, or understanding scores in simple games. These subtraction problems strengthen working memory and logical thinking, preparing their brains for more complex problem-solving. Mastery of subtraction-within-20 also reduces math anxiety, because students who feel secure with these facts approach harder math with courage rather than frustration.
The most common error at this age is losing track of the starting number when counting backward. For example, a child might count "15, 14, 13" and incorrectly say 13 is the answer to 15 - 2, because they counted three numbers instead of two steps back. Another frequent mistake is confusing which number to subtract from—a child might calculate 3 - 15 instead of 15 - 3. Watch for students who seem to restart from one each time rather than using efficient strategies; this signals they haven't yet internalized subtraction relationships. You'll also notice hesitation or finger-counting on every single problem, even for facts like 10 - 1.
Play a simple "subtraction story" game at home using small objects like crackers, coins, or building blocks. Give your child a pile of 15-20 items and say something like, "Imagine we're explorers with 14 granola bars. We eat 5 on our journey. How many do we have left?" Let them physically remove the items while you say the math sentence aloud together ("14 minus 5 equals 9"). This concrete, playful approach helps them see subtraction as something real, not just worksheet numbers. Repeat with different scenarios throughout the week—children this age need many repetitions with hands-on materials before automaticity clicks.