Stretching it Out

This activity focuses on length.
Many of the difficulties students have measuring lengths arise from their understanding of the ruler as a scale. Students also have difficulty with starting points or measuring from 0 on the ruler. This activity relates their repeated use of 1 centimetre lengths to a ruler.
Before students begin this activity, highlight appropriate and inappropriate ways to measure with the centimetre cubes. For example:

“What is wrong with saying that this pencil is 14 centimetres long?” This example illustrates the need for a baseline (starting point).

“Is this pen really 9 cubes long?” This example shows that a unit must be used consistently. This is vital to any scale.
Matching their marked-up strips to a real ruler will help students understand how rulers were first made. Having discovered this, students should be encouraged to put the unit idea to work. This will happen whenever one student gives another student instructions for drawing or building a structure.
For example:
“Make a joined line of multilink cubes that is 20 centimetres long.”
“Draw a square with sides that are 12 centimetres long.”
The second student’s building or drawing can be compared with the first student’s original measuring device.

Answers to Activity

1. a. 8 cm
b. 16 cm
c. 6.5 cm
d. 8 cm
e. 15.5 cm
f. 10 cm
g. 5 cm
h. 25 cm
2. No answer
3. Answers will vary.