Scavenger hunt

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Purpose

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.

Achievement Objectives
GM2-2: Partition and/or combine like measures and communicate them, using numbers and units.
Specific Learning Outcomes
  • Find objects that they estimate to be 1cm, 10cm, 50cm and one metre long.
  • Measure lengths of approximately one metre to the nearest cm.
Description of Mathematics

Children need to recognise the need to move from using non standard to standard measures of length. The motivation for this arises out of students comparing differences in the lengths of different objects (e.g. in the length of their hand spans). From this the need for standard measurement becomes evident.

Students also need to develop personal benchmarks with which they can measure various objects in their daily lives. Their personal benchmarks need to gradually relate more to standard measures such as metres and 1/2 metres.

Ultimately, students should able to choose appropriately from a range of strategies including estimation, knowledge of benchmarks, and knowledge of standard measures to approach various measuring tasks with confidence and accuracy.

Opportunities for Adaptation and Differentiation

This unit can be differentiated by varying the scaffolding of the tasks or altering the difficulty of the tasks to make the learning opportunities accessible to a range of learners. For example:

  • carrying a paper strip of the target length for part of their hunt
  • providing a 'hint station' with clues of suitable objects around the class.

This unit can be adapted to acknowledge student interests and contexts encouraging engagement. For example:

  • The scavenger hunts could be carried out in different locations (e.g. the classroom, in the school playground, at a local park or marae).

Te reo Māori vocabulary terms such as ine (measure), mita (metre), mitarau (centimetre), whakatau tata (estimate), and paerewa (benchmark) could be introduced in this unit and used throughout other mathematical learning.

Required Resource Materials
Activity

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. Consider grouping together students with mixed mathematical abilities in order to encourage collaboration (mahi tahi) and tuakana-teina (peer supported learning).

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.

Introduce the concept of a scavenger hunt, and model how to complete the tasks at each station. Depending on the needs of your students, it may also be appropriate to model how to accurately measure items with a ruler. This modelling could be used to create a class chart or set of guidelines for measuring. In turn, this could be used to support students in practising accurate modelling skills throughout the session.

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 1)

Go on a Scavenger Hunt!

  1. Use a ruler to find out how long 1 cm is. Take a good look!
  2. Find ten objects that you estimate to be 1cm long.
  3. Record your objects on the table below.
  4. Check your estimations using a ruler to measure the length of the objects accurately.
Object with estimated length 1cmMeasured 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 (Copymaster 2)

Go on a Scavenger Hunt!

  1. Use a ruler to find out how long 10cm cm is. Take a good look!
  2. Find ten objects that you estimate to be 10cm long.
  3. Record your objects on the table below.
  4. Check your estimations using a ruler to measure the length of the objects accurately.
Object with estimated length 10cmMeasured 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 3)

Go on a Scavenger Hunt!

  1. Use a ruler to find out how long 50cm is. Take a good look! This length is also known as half a metre. Why?
  2. Find ten objects that you estimate to be 50cm long.
  3. Record your objects on the table below.
  4. Check your estimations using a ruler to measure the length of the objects accurately.
Object with estimated length 50cmMeasured lengthDifference 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 4)

Go on a Scavenger Hunt!

  1. Use a ruler to find out how long 1 metre is. Take a good look! What is another name for this length?
  2. Find ten objects that you estimate to be 1 metre long.
  3. Record your objects on the table below.
  4. Check your estimations using a ruler to measure the length of the objects accurately.
Object with estimated length 50cmMeasured lengthDifference 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?

Reflecting – Class activity

  1. 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.
  2. 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.

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Level Two