# Chapter 9: CK-12 Algebra Explorations Concepts, Grade 7

**At Grade**Created by: CK-12

## Introduction

In these concepts, you will continue to develop eight key concepts of algebra and will practice your problem solving skills. There are eight concepts, and each one focuses on a key algebraic thinking strategy. You will focus on describing, identifying your job, planning, solving, and checking your thinking.

- 9.1.
## X for Unknown

- 9.2.
## Letter Grids

- 9.3.
## Hanging Scales 7

- 9.4.
## Speedo

- 9.5.
## Lines of Numbers

- 9.6.
## Fruit Confusion

- 9.7.
## Yummy Yogurt

- 9.8.
## Pedal Power

### Chapter Summary

## Summary

In these concepts we used proportional reasoning when we determined the weights and costs of fruits, when we applied the \begin{align*}D=rt\end{align*} formula, and when we determined the nature of positions of numbers in a repeating pattern. We thought about equality and inequality when we used the order of operations and the distributive property, and when we solved equations. We saw variables as unknowns when we modeled systems of equations in letter grid problems and scale problems. We also saw variables as varying quantities when we completed tables for functions and applied the distance-rate-time formula to solve problems. We wrote equations to represent weights of blocks pictured on scales, relationships between pairs of data in tables, and relationships among distance, rate, and time. In many of the concepts we practiced interpreting representations of mathematical relationships, like when we looked at circle and arrow grid diagrams, weight scales, line graphs, and tables of data.