Missing addends within 5 worksheets introduce the foundational concept of algebraic thinking. Unlike standard addition where the sum is unknown (2 + 3 = ?), these problems require students to find a missing part of the equation (2 + __ = 5).

The Logic of Missing Numbers This activity shifts the focus from simple calculation to problem-solving. It tests the student’s understanding of part-part-whole relationships.

Solving Strategy: Counting On To use this worksheet effectively, students should use the “Counting On” method.

Start with the known number (e.g., 2).
Count up until reaching the total (e.g., 5).
The number of steps taken (3) is the missing addend.

The worksheet includes visual counters next to the numbers to assist students in visualizing the gap between the known part and the whole sum.