Mystery Addends: Representing Word Problems

Beginning

• Begin by providing a concrete model of solving for a missing addend. Use a cup and circular counters. Tell students, "I have ten circles total. I am hiding some circles under this cup. There are four circles outside the cup. How many circles am I hiding?"
• Allow students time to think about the problem and explain their thinking. Accept all answers before displaying the hidden counters. Continue with a few more examples using ten total counters.

Intermediate

• Define "initial" as the amount that you start with. Write __ + ? = __ on the board to guide the students in solving the problem.
• Encourage students to explain their thinking as they discuss solving the word problem. Some students may solve addend unknown problems using addition, while others may use subtraction. Accept different strategies as viable approaches for solving the problem.

Beginning

• Read the problem once, and tell students to turn and talk to a partner to desribe the situation in their own words.
• If possible, provide a word problem in students' home language (L1).
• Use a question mark rather than a triangle to represent the mystery addend.

Intermediate

• Challenge students to explain how they might use both addition and subtraction to solve problems involving a mystery addend.
• Instruct a student write the fact family that corresponds to the word problem on board.

Beginning

• Read each problem aloud as a class. Sketch the scenarios presented in the word problems, and clarify unfamiliar vocabulary.
• If possible provide word problems that involve solving for a missing addend in students' L1.

Intermediate

• Instruct students to restate the problems using their own words to a partner.
• Invite students to write word problems that involve solving for a missing addend. Exchange problems with a partner.