Missing Number Sentences and Equations: Grade 3 math

What this covers

Missing Number Sentences and Equations is taught in Grade 3 (age 8 to 9) as a main teaching focus. It sits in the Algebra strand.

Worked example

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

1. Missing addend or subtrahend within 20 with unknown at end (e.g., 8 + __ = 15)
2. Missing values within 50 with unknown at start or middle (e.g., __ - 6 = 23)
3. Missing values within 100 involving two-digit addition or subtraction
4. Equations with operations on both sides (e.g., 24 + __ = 50 - 12)
5. Equations involving basic multiplication or division facts with missing terms

Common mistakes

• Treating the equals sign as a command to compute rather than a statement of balance
• Applying the wrong inverse operation (e.g., calculating 50 - 20 instead of 50 + 20 for __ - 20 = 50)

Curriculum links

Indicative matches to Common Core State Standards. Check wording and codes against the official document.

• 3.OA.D.8 Solve two-step word problems involving the four operations and assess the reasonableness of answers.