In this unit we explore the size of a centimetre, construct centimetre rulers, and then use these rulers to measure the length of objects.
When students can measure lengths effectively using non-standard units, they are ready to move to the use of standard units. The motivation for moving to this stage often follows from experiences in which students have used different non-standard units for measuring the same length. They can then appreciate that consistency in the units used allows for easier and more accurate communication of length measures.
Students' measurement experiences must enable them to:
The usual sequence used in primary school is to introduce the centimetre first, then the metre, followed later by the kilometre and the millimetre.
The centimetre is often introduced first because it is small enough to measure common objects. The size of the centimetre unit can be established by constructing it, for example by cutting 1-centimetre pieces of paper or straws. Most primary classrooms also have a supply of 1 cm cubes that can be used to measure objects. An appreciation of the size of the unit can be built up through lots of experience in measuring everyday objects. The students should be encouraged to develop their own reference for a centimetre, for example, a fingertip.
As the students become familiar with the size of the centimetre they should be given many opportunities to estimate before measuring. After using centimetre units to measure objects the students should develop their own centimetre rulers, and be introduced to the standard centimetre ruler. Some classrooms have linked cubes which can be joined to form 10 cm rulers. Alternatively pieces of drinking straw could be threaded together.
The correct use of a ruler to measure objects requires specific instruction. The correct alignment of the zero on the ruler with one end of the object needs to be clarified.
Metres and millimetres are established using a similar sequence of experiences: first construct the unit and then use it to measure appropriate objects.
The learning opportunities in this unit can be differentiated by providing or removing support to students and by varying the task requirements. Ways to differentiate include:
The activities in this unit can be adapted to make them more interesting by adding contexts that are familiar to students. The clothing you are collect measurements for could be for a hypothetical sports top for your class, or for a new school uniform.
Te reo Māori kupu such as ine (measure), estimate (whakatau tata), mitarau (centimetre), and roa (length, long) could be introduced in this unit and used throughout other mathematical learning. You could also encourage students, who speak a language other than English at home, to share the words related to measurement that they use at home.
Dear families and whānau,
This week we have been measuring with centimetres. We started measuring with centimetre cubes and then made our own centimetre rulers.
At home this week your child has been asked to measure things with their centimetre ruler.
As a challenge see if you can find objects that when you join then together you get they measure a 100 cm. Draw a picture of your objects and their lengths.
Printed from https://meaningfulmaths.nt.edu.au/mmws/nz/resource/all-about-me at 8:44pm on the 26th February 2024