Grade
3
Mobile Math: Balance the Triangle
Look at the mobile below. What do you notice? What do you wonder?
Find the missing values so that the mobile is balanced.
![A mobile with 2 strings is balanced. The left string has 1 triangle. The right string has 1 square and 2 trapezoids. The value of the triangle is 39. The value of the square is 21.](/sites/default/files/styles/large/public/inline-images/zbftMUhiDLLQDsJsSe641746IeNVvDUOieUSkLrRcFUXua9GSW.png?itok=UpdlTXyn)
If the value of the trapezoid is now 11, how can you change the value of the square so that the mobile remains balanced?
![A mobile with 2 strings is balanced. The left string has 1 triangle. The right string has 1 square and 2 trapezoids. The value of the triangle is 39. The value of the trapezoid is 11.](/sites/default/files/styles/large/public/inline-images/ghcUWJXzlepdcnGQO3KEnh7p15dHsxjuLfleVsbQsN3iFwI9VW.png?itok=JugS3k4s)
The total value of the mobile is up to you. What values could each of the pieces have that would allow the mobile to be balanced?
![A mobile with 2 strings is balanced. The left string has 1 triangle. The right string has 1 square and 2 trapezoids. The value of each shape is up to you.](/sites/default/files/styles/large/public/inline-images/fxZvp2V94DjuwJvzN4prkqrpjLGTAAGuhiDECx9WfkxTn54K0p.png?itok=KLWwN238)
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Reference for Educators
Sample problems and solutions