:Measures
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Approach: One to one Level: Year 4 and year 8
Focus: Estimating measurements.
Resources: Ruler; measuring tape;objects: bolt, pencil, stick, ribbon.
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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.

 
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