How long does it take?

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Purpose

This unit involves students in looking at the lengths of time various activities take and calculating how long is spent on these activities in a week.

Achievement Objectives
GM2-1: Create and use appropriate units and devices to measure length, area, volume and capacity, weight (mass), turn (angle), temperature, and time.
Supplementary Achievement Objectives
NA2-1: Use simple additive strategies with whole numbers and fractions.
Specific Learning Outcomes
  • Estimate the time taken for daily activities in hours and minutes.
  • Use advanced counting or partitioning strategies to solve problems involving minutes and hours.
  • Check the reasonableness of answers obtained using a calculator.
Description of Mathematics

Two aspects of mathematics are explored in this unit on time:

  • Investigations of the length of time taken for various activities, working in hours and minutes.
  • Calculations involving hours and minutes. It is anticipated that ākonga could use repeated addition, skip counting, multiplication or division to solve these problems.
Opportunities for Adaptation and Differentiation

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

  • using materials or draw diagrams to support their thinking as they solve problems involving numbers of minutes and hours.
  • providing simplified tasks for ākonga to investigate, working with small numbers of minutes that add to less than an hour. For example, 2 minutes to brush your teeth (28 minutes total in a week), 5 minutes to make a sandwich for school lunch (25 minutes total in a week), or 3 minutes to pack your school bag (15 minutes total in a week)
  • providing more complex tasks for ākonga to investigate that involve working with larger numbers of minutes, that add to more than an hour. For example, 30 minutes of homework each school day (2 ½ hours in a week), or 10 hours sleep each night (70 hours sleep in a week)
  • using calculators to check the reasonableness of estimations.

The contexts in this unit can be adapted to recognise diversity and encourage engagement. For example, ask ākonga to share activities that happen regularly in their families, or activities that they regularly enjoy (for example, going to church, kapa haka practice, sports practice). Adapt the investigations to include these familiar and enjoyable activities.

Te reo Māori vocabulary terms such as wā (time), meneti (minute), and haora (hour) could be introduced in this unit and used throughout other mathematical learning.

Activity

Getting Started

  1. Begin a discussion about activities that ākonga are involved in every week.
  2. Brainstorm a list of things such as sleeping, playing, and eating.
  3. Once the list is compiled, discuss how often the activities occur. Are they daily, just on school days or a few times a week?
  4. Explain that this week they are going to look more carefully at some of these activities and work out how long they spend on them over the course of a week.
  5. Have ākonga work in pairs (a tuakana/teina model could work well here) to choose one of the activities from the list, and calculate how long they spend on this activity each week. Copymaster 1 can be used to help guide this process. Ākonga could present their findings digitally, in writing, or verbally. You can support ākonga to select which activity to focus on to ensure the process is not too complicated. Alternatively, ākonga who are ready for extension could be encouraged to think about multiple activities. 
  6. As ākonga work, help them with the numbers involved and discuss the strategies they are using.
    How could we work out what seven lots of 2 are all together?
    How do you know 5 lots of 5 minutes is 25 minutes altogether?
    How could you check?
  7. Encourage ākonga to discuss the methods they are using. If ākonga are familiar with the + and - symbols and their meaning, use the calculator as a way for ākonga to confirm their answers. Encourage students to check the answers the calculator gives them are reasonable.
    If we know 2 lots of 5 are ten is it reasonable for 5 lots of 5 to be 8 which is less than that?
  8. At the conclusion of the session bring all ākonga together to report and discuss their findings.
    How long do you think you would spend brushing your teeth in a week? What did your group find out?
    From our calculations which activity takes the most of our time over the course of a week? Which takes the least?
  9. Emphasise that the calculations they have done are based on estimates and are not statements of fact.

Exploring

  1. Show ākonga Copymaster 2.
  2. Over the course of the next few days look at the statements individually and assess whether or not they are reasonable. You need not look at all the statements, but work at the pace of your ākonga and cover as many as appropriate.
  3. For each statement have ākonga work in pairs to do their own calculations to check the statements. Copymaster 3 can be used to guide this process.
  4. Encourage ākonga to compare their ideas about what times they think are reasonable for the various activities as well as their methods for calculating to check the statements.
  5. A calculator could be used as a final check. Ākonga should be encouraged to confirm the reasonableness of the answers provided with mental calculations.
  6. At the end of each session have ākonga share their findings. The types of questions you might use to help develop their understanding include:
    How many minutes in an hour? In half an hour?
    How did you work out how long she spends each day?
    How could you check your calculations?
    Is it reasonable to spend that long to brush your teeth? How long do you think it takes you?
  7. Show ākonga Copymaster 4. Use the same process as above to decide which statements are reasonable and which ones are unreasonable.
  8. Compare the times taken by Sally for the various activities, with those taken by Hone.
    Who takes the longest?
    How much longer do they take?
    How does this compare with how long you would take to do that?
    Copymaster 5 can help in these comparisons.

Reflecting

  1. Have ākonga work in pairs to write their own set of statements about the time spent on different activities in a week.
  2. Get ākonga to write three statements but make only two of them reasonable and one unreasonable. Copymaster 6 can be used to record their statements.
  3. Once the statements are written, have the pairs of ākonga swap statements and work out which one of the other group’s statements is unreasonable.
  4. Can they describe to the other group how they found it and why they think it is unreasonable? Does the other group agree?
  5. As a conclusion to the session, have ākonga share their experiences.
    Did you find the statement that was unreasonable? How?
    What made you think it was the unreasonable one? How did you check?
  6. Discuss both the strategies used in calculations to check the reasonableness of the answers and the lengths of time taken for various activities. Discussion may cover debate about what is a reasonable length of time taken for a particular activity if required.
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Level Two