# Just a minute

Purpose

In this unit the students develop an understanding of the duration of minutes and seconds. We also practice reading time by counting the minutes after the hour.

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.
Specific Learning Outcomes
• Recognise the length of a minute.
• Recognise the length of a second.
• Tell time after the hour by counting minutes.
Description of Mathematics

Students' experiences with time throughout the learning sequence is focussing on two aspects - duration and telling time. However, before using the unit, ensure that children understand the notion of succession. This is the sequential ordering of time; years, days weeks, and months are arranged in succession.

Duration

The minute is often introduced first because it is small enough to measure common events. The duration of a minute can be established by watching the second hand on a clock or by constructing a minute sand-timer. An appreciation for the size of a minute can be built up through lots of experience in measuring everyday events. For example, how many minutes does the song play for? How long is morning break? How long does it take to walk around the school building? How many times can you hop in a minute? How many linked cubes can you join in a minute?

As the students become familiar with the size of a minute they should be given opportunities to estimate before measuring. Minutes need to be linked to the movement of the minute hand on the analogue clock and the digits on digital displays.

An understanding of the size of a second can be developed by investigating the relationship between seconds and minutes. This can be done by watching the digital displays on some watches, on stopwatches and on video-recorders. The students should be encouraged to develop their own reference for a second, for example, a counting pattern "one – banana – two – banana – three etc".

Students are likely to be able to read the time to the hour and half-hour prior to fully developing a conceptual understanding of the size of time units. In this unit we read clock time after the hour by counting the minutes after the hour and record this using digital notation.

Telling time must enable students to:

1. develop an understanding of the size of the units of time. This includes being able to estimate and measure using units of time.
2. read and tell the time using both analogue and digital displays.

The learning opportunities in this unit can be differentiated by providing or removing support to students and varying the task requirements.  Ways to support students include:

• Numbering large paper plates 1-12 on one side and 5 – 60 on the other side. Ask 12 children to make a large clock. The other children give directions of where they should put their plate. When they have completed the task it can be extended by turning over the plates to show the 5 minute intervals.
• Vary the previous activity by using fractions. For example, ‘If I wanted to cut the clock in half, by starting at 12, what number would I end on so that I have two halves.’ ‘If I wanted to cut the clock into fourths/quarters which is the best way to show the four fourths/quarters?’
• This can be further adapted by using angles. For example, ‘I know the hour hand is on 12, what number will the minute hand point to so that a right angle can be seen?’
• Draw their own clocks and compare to a large analogue clock
• Align a number line 0-60 with the clock

The context for this unit can be adapted to suit the interests and experiences of your students. For example:

• Explore other cultures that may use the 24 hour clock. One example is Italy. People in the military and business people who travel through different time zones also use 24 hour language. For example, 1600 hours is 4pm so that they are not confused with am and pm.
• Discuss how Māori and new settlers managed time. How did Māori know when to get up or how did early settlers know when to go to school? (Early Māori were governed by the rising and setting of the sun, seasons and phases of the moon. Most early settlers could not afford watches, so bells were rung for school, work and church).
Required Resource Materials
• Empty 250 ml drink bottles ( cut the base off the bottle and pierce a small hole in the bottle top)
• Dry sand (or salt)
• Paper cups
• Sand timers from Session 1
• Paper for the Just a Minute book
• Analogue clock (with minutes marked)
• Digital clock
• Clock with second hand
• Digital watches
• Start and End time recording sheet
Activity

#### Station 1: Minute timers

In this activity we develop an understanding of the duration of a minute by making our own salt timers.

Resources:

• Empty 250 ml drink bottles ( cut the base off the bottle and pierce a small hole in the bottle top)
• Dry sand (or salt)
• Paper cups
1. Begin with the students standing. Ask them to sit down when they think a minute has passed.
How did you decide when to sit down?
What could we use to check?

2. Look at a minute passing:
• Using the second hand of an analogue clock
• Using a cooking clock timer
• Watching the digits change on a digital clock

3. Show the resources and ask the students for their ideas about what we could be making. Tell the students that they are going to work in pairs to make their own minute timer. Demonstrate how putting sand or salt in the upside down drink bottle allows the salt to "drip" into the empty paper cup.
How could we use this to measure a minute? (find the appropriate amount of sand)

4. Let the students work in pairs to make their own minute timer. Share and check timers.

#### Station 2: Just a minute

In this activity we explore all the different activities that we can complete in a minute.

Resources:

• Sand timers from Session 1
• Paper for the Just a Minute book
1. Begin by asking the students how many times they think they could write their name in a minute. Share some estimates.

2. Get two volunteers to write their names on the board while the rest measure a minute using one of the sand timers constructed in session 1. When the minute is up count the number of names.
3. Brainstorm together for other things that they could try to complete in a minute.
• counting by ones
• hopping
• heart beats
• jumping jacks

4. List these on the board for the students to refer to.

5. Let the students work in pairs doing the things on the list. Ask them to make a recording of each activity for compiling in the "Just A Minute" book.

#### Session 3: Minutes after the hour

In this activity we practice reading time by counting minutes after the hour.

Resources:

• Analogue clock (with minutes marked)
• Digital clock
1. Begin by looking at the minute hand on the analogue clock.
How long does it take the minute hand to get around the clock face once?

2. Ask the students a number of questions about the time it takes for the minute hand to move between numbers on the clock. Check by counting (in ones until the students notice that you can count in fives).

3. Move the hands on the analogue clock to 20 minutes after 9. Ask:
What time is on the clock?
How do you know?
Can anyone tell me what 20 minutes after 9 would look like on the digital clock.

4. Repeat with other examples (initially limit this to minutes after the hour).

5. List times on the board for students to draw clocks. Include both digital and analogue times.
For example:
• Half past 3
• 7:15
• 25 minutes past 7.
• 2:40
• 18 minutes past 10.

#### Session 4: Wait a second

In this activity the students are encouraged to develop their own reference for a second, for example, a counting pattern "one – banana – two – banana – three etc".

Resources:

• clock with second hand
1. Look at the second hand on the clock.
How long does it take for the second hand to travel once around the clock?

2. Ask for a couple of volunteers to stand at the front of the class(facing away from the clock). Ask them to put their hand up when they think 10 seconds has passed.

3. Repeat with another two volunteers.

4. Brainstorm ideas for estimating seconds.

5. Let the students work in pairs to find their own method for estimating seconds. Ask them to record their method on a piece of paper for sharing.

6. Share and check the accuracy of methods.

#### Session 5: Timing activities

In this session we record the start and end times of a number of activities

Resources:

1. Begin by posing the question:
How long does it take to write your full name on the board?

2. Ask for a volunteer to give their estimate. As the volunteer writes her/his name ask the rest of the class to use their checking methods from session 4.

3. Brainstorm a list of activities that will take a short time to complete (but longer than a minute). For example:
• Completing the daily printing task
• Writing the digits to 100
• Eating an apple