Unit 4, Lesson 2
Keeping the Equation Balanced
Grade 8
2.1
Warm-up
Notice and Wonder: Hanging Objects
What do you notice? What do you wonder?
Sign in to view assessments and invite other educators
Sign in using your existing Kendall Hunt account. If you don’t have one, create an educator account.
What do you notice? What do you wonder?
A triangle weighs 3 grams, and a circle weighs 6 grams.
If we have equal weights on the ends of a hanger, then the hanger will be in balance. If there is more weight on one side than on the other, the hanger will tilt to the heavier side.
We can think of a balanced hanger as a representation for an equation. An equation says that the expressions on each side have equal value, just like a balanced hanger has equal weights on each side. This hanger could be represented by
If we have a balanced hanger and add or remove the same amount of weight from each side, the result will still be in balance. Here, we remove 2 triangles from each side, which is like subtracting
In the same way that adding or subtracting the same shapes on each side of a hanger keeps it in balance, adding or subtracting the same value to each side of an equation creates an equivalent equation.
Help us improve by sharing suggestions or reporting issues.