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This Mixed Add Subtract drill has 48 problems for Grade 3. Earth Day theme. Answer key included.
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Max discovered pollution spreading through the forest—he must solve equations fast to clean up before animals return home!
Standard: CCSS.MATH.3.NBT.A.2
Preview
Page 1 — Drill
Page 2 — Answer Key
What's Included
About this Grade 3 Mixed Add Subtract Drill
By Grade 3, students need to fluently solve problems that mix addition and subtraction in a single expression—a skill that mirrors real-world math they encounter daily. When children track allowance earnings and spending, calculate remaining Halloween candy, or help plan an Earth Day community cleanup by adding supplies and subtracting those already used, they're doing mixed-add-subtract. This competency strengthens their number sense and prepares them for multi-step word problems and eventually algebra. At ages 8–9, students are developing the mental stamina to hold numbers in working memory while performing two operations. Mastering this skill builds confidence and automaticity, reducing cognitive load so their brains can focus on problem-solving strategy rather than computation.
What your student will practice
- Solve two-operation expressions (add then subtract, or subtract then add) accurately
- Apply left-to-right order of operations for same-priority operations
- Identify which operation to perform first when reading mixed expressions
- Check answers using inverse operations to verify correctness
Common mistakes to watch for
Many Grade 3 students reverse the order of operations, subtracting first when they should add first—for example, solving 15 + 8 – 5 as 15 – 8 + 5, arriving at 12 instead of 18. Others lose track of the running total after the first operation and forget what number to use in the second step. Watch for students who write 15 + 8 = 23, then suddenly jump to a different starting number for subtraction, or those who consistently perform whichever operation they see second. Asking them to underline or say aloud which operation comes first helps expose this pattern.
Play a 'store game' at home: name a starting amount (e.g., 20 dollars), then take turns calling out purchases (subtract) and earnings from chores (add) in random order. Have your child keep a running total on paper, writing the full expression as they go. This mirrors real transactions while anchoring the left-to-right rule in a game context. Over time, increase the numbers and complexity, and your child will internalize the sequence naturally through repeated, purposeful play rather than drill worksheets alone.