Strip Diagram: Part-Whole [TEKS Tools Grade 3]

This post specifically looks at how part-whole strip diagrams can be used to solve a variety of problems. Read more about TEKS Tools and their rationale here.

Strip Diagram

Strip diagrams, the first TEKS Tool, account for around 40% of each 3rd grade STAAR test. Within this tool are many variations: part-whole, equal groups, and comparison (the first two being the primary types of strip diagram used).

The main function of a strip diagram is to show the relationship between the quantities in the problem situation. When the relationship is evident, students can select the correct operations and perform accurate calculations.

One thing to note about strip diagrams is that the total can be shown in a variety of ways and positions. I rotate how I represent the total to match the various representations seen on STAAR.

Part-whole

Part-whole relationships are used to solve problems involving addition and subtraction. There are several TEKS listed below that include these operations.

3.4A - solve with fluency one-step and two-step problems involving addition and subtraction within 1,000 using strategies based on place value, properties of operations, and the relationship between addition and subtraction

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2023-9: the parts were given, students had to solve for the missing total

2024-1: the total and a part were given, students had to solve for the missing part

2025-16: the total (in two parts) and a part were given, students had to solve for the missing part

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3.5A - represent one- and two-step problems involving addition and subtraction of whole numbers to 1,000 using pictorial models, number lines, and equations

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2023-7: the total and a part were given, students had to solve for the missing part

2023-24: one part was given, one part could be found with a comparison, students had to solve for the missing total

2024-7: the total and a part were given, students had to solve for the missing part

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3.7B - determine the perimeter of a polygon or a missing length when given perimeter and remaining side lengths in problems

Before the formal introduction of a formula, a part-whole strip diagram can be used to solve problems involving perimeter.

Click on each > to expand.

2023-21: one side length (part) and perimeter (total) were given, students had to solve for the missing side length (part)

2024-6: side lengths (parts) are given, students had to solve for the perimeters (totals)

2024-18: one side length (part) and perimeter (total) were given, students had to solve for the missing side length (part)

2025-11: side lengths (parts) were given, student had to solve for the perimeter (total)

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3.8B - solve one- and two-step problems using categorical data represented with a frequency table, dot plot, pictograph, or bar graph with scaled intervals

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2024-14: multiple parts and the total were given, students had to solve for the missing part