Education Technology

Expressions and Equations / Visualizing Equations Using Mobiles

Grade Level 6,7
Activity 7 of 18
In this lesson students explore interactive mobiles for modeling one or more equations. Students are given specific constraints and use solution preserving moves to reinforce the understanding of how equations work.

Planning and Resources

Students should be able to associate moves that preserve balance in a mobile with moves that preserve equivalence of two expressions and determine solutions that can be converted to the form ax = b and x + a = c.


Standard: Search Standards Alignment


Lesson Snapshot


Students understand how mapping a balanced mobile to an equation provides a foundation for reasoning about strategies for solving equations.

What to look for

Some students may reason about the numerical value for each expression in an equation and how they must be the same, while others may reason by identifying numbers that make the mobile unbalanced and in which direction.

Sample Assessment

If 3c + b = 2b and b = 18 what is c?

Answer: c = 6

The Big Idea

Mobiles can be used as a visual/physical model to leverage student reasoning about an equation involving two variable expressions in terms of balance between weights on mobiles.

What are the students doing?

Students reason about the values of weights on mobiles and use balance to model solution preserving moves algebraically.

What is the teacher doing?

Encourage students to use the way the mobile behaves to reason about the values of weights on the mobile and relate that to the values of variables in an equation.