Number Lines: Proportionality [TEKS Tools Grade 8]

This post specifically looks at how number lines can be used solve problems involving proportional relationships. Read more about TEKS Tools and their rationale here.

Number Lines

Number lines account for around 14% of each 8th grade STAAR test. These number lines are applied to solve problems related to rates, ordering numbers, similar shapes, and direct variation.

The main function of a number line is to solve problems involving rates, direct variation and proportionality, and to visualize ordering rational and irrational numbers. By visualizing these quantities on number lines, students can better make sense of the how the quantities are related.

---

Similar Shapes

8.3A - generalize that the ratio of corresponding sides of similar shapes are proportional, including a shape and its dilation

Click on each > to expand

2023-38: two similar shapes were given, students had to identify the correct proportion

2024-6: two similar shapes were given, students had to identify the correct proportion

---

Direct Variation

8.5E - solve problems involving direct variation

Click on each > to expand

2024-23: two proportional values were given, students had to find a fourth when given a third

2025-20: two proportional values were given, students had to find a fourth when given a third

---

8.5F - distinguish between proportional and non-proportional situations using tables, graphs, and equations in the form y = kx or y = mx + b, where b ≠ 0

Click on each > to expand

2023-7: four tables were given, students had to identify the one with a proportional relationship