Approach: One
to one 
Level:
Year 4
and year 8 

Focus:
Estimating measurements. 
Resources:
Ruler; measuring
tape;objects: bolt, pencil, stick, ribbon. 

128KB 


Questions/instructions:
Do not let the student see a ruler or the measuring tape until it is time
to make the actual measurements.
In this activity I am going to ask you to estimate or guess the length
of some things. After that, you can measure them to check your estimates.
I’ll write down the measurements you tell me. Each time, tell me
if the measurement is in millimetres, centimetres or metres.
One at a time, introduce each of the objects in the order given. Ask
student to estimate all of the objects before they are measured. Write
student’s answers for each measure. 

%
responses
2001 '97

y4

y8

Hand
student the bolt. [70mm]
1. How long do you think this is?
Prompt: What are the units of measurement?
Record student answer. 
56–84mm

26
(27)

42
(38)

42–55mm
or 85–98mm

20
(25)

29
(32)

Hand
student the pencil. [144mm]
2. How long do you think this is?
Prompt: What are the units of measurement? 
115–173mm

20
(26)

36
(38)

89–114mm
or 174–203mm

35
(35)

41
(40)

Hand
student the stick. [302mm]
3. How long do you think this is?
Prompt: What are the units of measurement?

240–360mm

33
(34)

63
(63)

180–239
or 361–420mm

19
(23)

20
(23)

Hand
student the ribbon. [400mm]
4. How long do you think this is?
Prompt: What are the units of measurement?

320–480mm

23
(24)

50
(44)

260–319
or 481–560mm

20
(24)

28
(35)

5.
Now how tall do you think you are?
Prompt: What are the units of measurement? 
Closeness
to teacher’s measurement in question 6:



within
20%

45
(39)

74
(78)

within
20–40%

14
(10)

7
(9)

Give
the student the ruler (not the measuring tape).
Now I want you to use this ruler to measure the length of each of the
four things. As you measure them, tell me what the length is, and I’ll
write it down. Remember to tell me the unit of measurement.

•
bolt

65–75mm

79
(79)

95
(97)

•
pencil

130–150mm

87
(88)

98
(98)

•
stick

290–310mm

91
(93)

98
(99)

•
ribbon

390–410mm

51
(56)

89
(93)

Now
let’s see how tall you are.
Have student stand against a wall. Place a piece of tape on the wall
to show the height. Give student the measuring tape.
6. Now measure your height and tell me how tall you are so I can write
it down. Remember to tell me the unit of measurement.
Record student answer. Check student’s measurement and record
actual height.

within
3cm

69
(76)

73
(77)

Commentary:
Both year 4 and year
8 students were quite inaccurate in estimating the lengths of four objects.
Most year 8 students measured accurately, except where the length to
be measured was greater than the length of the measuring device. There
was little change in performance between 1997 and 2001.
