Problem
Add the circles in every column: 2 + 2 + 4 + 1 = 9 circles in all.
Reading and totaling the symbols is how you interpret a scaled picture graph.
3.MD.B.3Identify Subproblems9 circles stand for 18 students, so one circle stands for 18 ÷ 9 = 2 students.
Sharing 18 students equally among 9 circles tells the value of each circle (the scale).
3.MD.B.3Analyze The UnitsEach circle in the graph stands for 2 students.
The 9 circles together stand for all 18 students and every circle is worth the same amount, so one circle's value is 18 split evenly into 9 equal parts.
The 18 students are exactly the students shown by the circles, with none left out and none counted twice, so the circle amounts add back up to 18.
Nine equal circles building up to 18 students is a multiplication, so the size of one circle is found by reversing it with division.
Nine circles each worth the same is nine equal groups, and counting equal groups is exactly what multiplication does, so 9 times one circle's value is 18.
Division is the reverse of multiplication, so from 9 times one circle equals 18 we get that one circle equals 18 divided by 9.
Town C has 4 circles and each circle is 2 students, so Town C has 2 × 4 = 8 students.
Multiplying circles by students-per-circle gives the town's real value.
3.MD.B.3Analyze The UnitsThis only needs the Grade 3 idea that one picture stands for a set number — find that, then multiply!