Inches and centimetres

Inches and centimetres

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This task is about converting between inches and centimetres.
Maxine was helping her Grandad build a mouse cage. His plans were in inches, but Maxine liked using centimetres.
 
Maxine compared her ruler with her Grandad's.
 

Question 1Change answer

Maxine's ruler
Centimetres

 

 

Grandad's ruler
Inches

  [NOT DRAWN TO SCALE]
   
Using the rulers above, help Maxine convert each of these measurements.
 
a)  12 inches =   centimetres
 
b)  15 centimetres =    inches
 
c)  10 inches =   centimetres
 
d)  10 centimetres =   inches
 
e)  3 inches =   centimetres
 
f)   24 inches =   centimetres
 
g)  45 centimetres =   inches
Level:
3
Curriculum info: 
Maths, Geometry and Measurement, Measurement
Keywords: 
length, conversion of units, double number lines
Description of task: 
Students use diagrams of a metric and imperial ruler to convert between inches and centimetres.
Curriculum Links: 
This resource can help to identify students' understanding of converting between different measurement scales in length.
Answers/responses: 
  

Y7 (03/1999)
a) 30 very easy
b) 6 very easy
c) 25 very easy
d) 4 easy
e) 7.5 [Accept 7 ½] very difficult
f) 60 moderate
g) 18 very difficult
Diagnostic and formative information: 
  Common error Likely reason
e) 7 or 8 Rounds 7.5 to nearest whole number.
e) 5.5 or 6 Assumes tick mark between 5 and 10 cm to be 0.5 or 1 cm.
f) 42 = 12 + 30 Adds cm and inches.