Grade
3

Mobile Math: Downhill Shapes

Look at the mobile below. What do you notice? What do you wonder? What do you know?

A mobile with a total value of 18. It has 3 strings of unequal value. The left string has 4 triangles and the least value. The middle string has 3 hexagons. The right string has 2 trapezoids and the greatest value. Each hexagon has a value of 2. What values do the triangles and trapezoids have?

This mobile is unbalanced. Is the value of the string with triangles greater or less than the value of the string with trapezoids? Why do you think so?

What is one set of possible values for the shapes?

  • What is the combined value of the two outer strings?
  • What values could the two outer strings have?

The mobile was unbalanced. Now the mobile is balanced. All three strings have the same value. The total value of the mobile is 72. The hexagon has a value of 8. What values can you give the triangle and the trapezoid that would balance the mobile?

The mobile has a value of 72. It is balanced across three strings. The left string has 4 triangles. The middle string has 3 hexagons. The right string has 2 trapezoids. Each hexagon has a value of 8. What values do the triangles and trapezoids have?

When the mobile is balanced, how many triangles have the same value as 1 trapezoid?

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Reference for Educators

Sample problems and solutions