In this unit students participate in a series of scavenger hunts to develop their own personal benchmarks for measures of 1cm, 10cm, 50cm and one metre. An understanding of the relationship between centimetres and metres is also developed.
 find objects that they estimate to be a 1cm, 10cm, 50cm and one metre long
 measure lengths of approximately one metre to the nearest cm
Children need to be able to see the need to move from using non standard measures of length to standard measures of length. The motivation for this will arise out of students comparing differences in the length of their hand spans etc. From this the need for standard measurement will become evident.
Students also need to develop personal benchmarks with which to measure various objects in their daily lives. Their personal benchmarks need to gradually relate more to standard measures such as metres, 1/2 metres.
The ultimate aim is for students to be able to choose appropriately from a range of strategies including estimation, knowledge of benchmarks, and knowledge of standards measures in order approach various measuring tasks with confidence and accuracy.
This unit is run as a series of stations over four days with students rotating around the stations in groups. The final session is run as a class activity with all students working on the same task in groups.
The four stations involve the students looking for objects that they estimate to be a certain length. You will need to set appropriate boundaries for their search, e.g. the classroom or the playground.
As students work, the teacher can circulate amongst the groups. Points to reinforce in your discussions with students include
 There are 100 centimetres in a metre.
How many 1 cm lengths in a metre?
How many 10 cm lengths in a metre?
Why is 50 cm sometimes called half a metre?
What is another name for a metre?  Estimation can involve the use of personal benchmarks e.g. knowledge that your fingernail is 1cm long or the length of your stride is 1m can help you estimate these lengths more accurately.
 To measure accurately, one end of the object being measured must be aligned with zero on the ruler.
 The meaning of the unmarked gradations on the ruler may need to be considered. Measurement to the nearest cm often requires identification of the number closest to the end of the object being measured.
Station One
Students work in pairs or small groups to find items that they estimate to be 1cm long. They check their estimates by measuring.
Student Instructions (Copymaster One)
Go on a Scavenger Hunt!
Object with estimated length 1cm  Measured length 






How accurate were your estimates?
Were your estimates too long or too short?
What would be a good way to try and remember how long 1cm is?
Station Two
Students work in pairs or small groups to find items that they estimate to be 10cm long. They check their estimates by measuring.
Student Instructions (Copmaster Two)
Go on a Scavenger Hunt!
Object with estimated length 10cm  Measured length 






How accurate were your estimates?
Were your estimates too long or too short?
What would be a good way to try and remember how long 10cm is?
Station Three
Students work in pairs or small groups to find items that they estimate to be 50cm long. They check their estimates by measuring.
Student Instructions (Copymaster Three)
Go on a Scavenger Hunt!
Object with estimated length 50cm  Measured length  Difference between estimated and measured length 









How accurate were your estimates?
Were your estimates too long or too short?
What would be a good way to try and remember how long 50cm is?
Station Four
Students work in pairs or small groups to find items that they estimate to be 1metre long. They check their estimates by measuring.
Student Instructions (Copymaster Four)
Go on a Scavenger Hunt!
Object with estimated length 50cm  Measured length  Difference between estimated and measured length 









How accurate were your estimates?
Were your estimates too long or too short?
What would be a good way to try and remember how long 1 metre is?
 Use a ruler to find out how long 1 cm is. Take a good look!
 Find ten objects that you estimate to be 1cm long.
 Record your objects on the table below.
 Check your estimations using a ruler to measure the length of the objects accurately.
 Use a ruler to find out how long 10cm cm is. Take a good look!
 Find ten objects that you estimate to be 10cm long.
 Record your objects on the table below.
 Check your estimations using a ruler to measure the length of the objects accurately.
 Use a ruler to find out how long 50cm is. Take a good look! This length is also known as half a metre. Why?
 Find ten objects that you estimate to be 50cm long.
 Record your objects on the table below.
 Check your estimations using a ruler to measure the length of the objects accurately.
 Use a ruler to find out how long 1 metre is. Take a good look! What is another name for this length?
 Find ten objects that you estimate to be 1 metre long.
 Record your objects on the table below.
 Check your estimations using a ruler to measure the length of the objects accurately.
Reflecting – Class activity
 Before the session, set up six activity stations around the room. At each station put a selection of paper strips in a variety of lengths. Ensure that at each station there are strips with a length of 1cm, 10cm, 50 cm and 1 metre. Label the strips at each station with letters.
 Tell the students they will be participating in the ultimate estimation challenge. Have the students rotate around the stations identifying the strips they believe to be 1cm, 10 cm, 50 cm and 1 metre long. They record their results on recording sheets (Copymaster Five).
At the conclusion of the session reveal the correct letters for the 1cm, 10cm, 50 cm and 1 metre lengths. Students check their answers and have a chance to measure the strips they chose as required.
Extension
Students who finish the activity early could estimate and measure the lengths of the other paper strips at the stations.
Family and Whanau,
This week in maths we are working on estimating lengths of up to a metre. Can you please help your child find an objects at home that they estimate to be 1cm, 10 cm, half a metre, and 1 m long? They can record the names of the object and the estimations in their book. Ask them to choose 1 object to bring to school so we can measure it carefully to check their estimation.