1st Grade Math Question of the Day

1. 10
2. 12
3. 13 (correct answer)
4. 14

Explanation: This question tests 1st grade ability to add three whole numbers with sum ≤20 (CCSS.1.OA.2). When adding three numbers, students can use helpful strategies to make it easier. One strategy is to look for two numbers that make 10 (like $6+4$ or $7+3$), add those first, then add the third number; another strategy is to look for doubles or numbers that are easy to add together, combine those first, then add the remaining number; students can add in any order because of the commutative and associative properties. The story presents three quantities: 6 pencils from Jamal, 4 pencils from Sofia, and 3 pencils from Chen. Choice C is correct because adding all three numbers gives $6 + 4 + 3 = 13$; we can add $6+4=10$ first, then $10+3=13$. Choice B is a common error where students only add two of the three numbers, such as $6+3=9$ or $4+3=7$, but here perhaps adding $6+4=10$ and forgetting to add 3, or making a calculation error like $6+4+3=12$ by miscounting; this happens because keeping track of three numbers is challenging and calculation facts may not be automatic. To help students: Use physical objects in three groups that students can count and combine; teach making-10 strategy explicitly with pairs that sum to 10; practice doubles facts ($3+3$, $4+4$, $5+5$); model different groupings using parentheses: ($6+4)+3$ or $6+($4+3$); use visual representations showing three groups; emphasize that order doesn't matter; have students explain their strategy; practice with various number combinations; connect to real contexts with three groups.