How long is a slinky?
In this unit students take part in a variety of measurement tasks including measuring the length of a slinky, working out how many slices of tomato will fit around the edge of a pizza and drawing the label from a can accurately.
describe a method to measure the length of circular objects
measure length using metres, centimeters and millimeters
calculate the circumference of a circle from a measurement of diameter
The measuring challenges in this unit invite students to engage in practical measuring tasks. In all tasks students are presented with a variety of measuring tools to complete the task and are asked to plan a method to solve the problem. Emphasis is on the measurement process, not the answer obtained, with students encouraged to describe their solutions and the thinking behind them. As these tasks involve measuring the circumference of a circle it would be appropriate to introduce the formula for this as a way of checking the measurements obtained.
Circumference = π x diameter
Additional items required for each station:
Station One
- slinky
- Copymaster 1
Station Two
- a variety of cans, with labels attached
- Copymaster 2
Station Three
- large pizza bases, or a paper circle to represent these ·
- Copymaster 3
Station Four
- Doughnuts: round and straight
- Copymaster 4
Station Five
- Several balls, netball size of similar. Ideally all balls the same size.
- Large sheets of paper, A1 size is ideal
- Copymaster 5
Copymaster 6 contains a general template that can be used to help students structure their work. This can be used by students at any of the stations as required.
Station One
In this station students work together to devise a way to measure the length of slinky: a coiled plastic toy. They will need to consider how to measure each ring and then multiply by the number of rings on the slinky, allowing for partial revolutions. Copymaster 1 contains student instructions for this activity.
Encourage students to plan their method for measuring before they begin and reflect on its success when finished. Introduce students to the formula for circumference as a way to check their measurements. (Circumference = π x diameter).
Have them measure the diameter and multiply this by pi (approximated by 3.14) to get a calculated circumference of one revolution. They can then compare this with the measurement made for one single revolution of the slinky.
Station Two
Students draw a diagram of the label on a can, taking measurements from the can to ensure their diagram is accurate. Diagrams can be drawn to any scale with the simplest being a one to one representation; alternatively you could specify a scale such as 2:1 or ask students to choose their own.
Students plan their method before they begin and assess its success at the end of the task. Possible methods include:
- Using a piece of string or paper strip to measure around the can and directly transferring this length to the diagram.
- Using a piece of string or paper strip to measure around the can, measuring the piece of string in cm and mm and using a ruler to draw the appropriate length line on the diagram.
- The height of the label can be measured directly using a ruler.
Students can verify the circumference by calculating the circumference of the can. Have them measure the diameter and multiply this by pi to get a calculated circumference.
Once all groups have finished this activity measurements can be checked by removing the label from the can for direct comparison with the diagrams drawn if the scale used in the diagram is one to one. Copymaster 2 contains student instructions for this task.
Station Three
In this station students estimate, then measure, how many slices of tomato will fit around the edge of a pizza. As students work encourage them to focus on the method used for measurement, planning their approach before they begin and evaluating it at the completion of the task. Copymaster 3 contains student instructions for this activity.
Note that students will need to consider how far from the edge of the pizza the tomato is placed. Using the diameter of the tomato pieces and the outside edge of the pizza base as the basis for the measurements will not work as tomatoes would then be hanging over the edge of the pizza. Students will need to measure the circumference of the pizza base at least 3.25 cm from the edge to allow for the width of the tomato slices.
 |
 |
 |
| Using the diameter of the tomato pieces and the outside edge of the pizza base as the basis for measurements. | Using the diameter of the tomato pieces and 3.25cm from the edge of the pizza base as the basis for measurements. | Using the diameter of the tomato pieces and greater than 3.25cm from the edge of the pizza base as the basis for measurements. |
Students could verify their answers by
- calculating the circumference of the position on the pizza base the tomatoes are to be placed. Have them measure the diameter across the pizza from the middle of the tomatoes and multiply this by pi to get a calculated circumference.
- Making circles of 6.5 cm diameter to represent the tomato and place them on the pizza base
- Repeating their measurements
Have students compare and justify results with other groups once the task is complete.
Station Four
Students measure the length of round and straight doughnuts to work out which is longer. The focus of the task is on the method used for measurement with students asked to describe their method as well as solve the problem. Copymaster 4 contains student instructions for this activity.
To complete this task, students will need to devise a way to measure the length of the round doughnut. One way would be to use a piece of string to measure around the doughnut and then measure the length of the string. Students will come up with other options. Encourage them to explore different methods. Students who complete this task easily could be challenged to draw diagrams of doughnuts in which the round and the straight ones are the same length.
Students can verify the circumference by calculating the circumference of the doughnut. Have them measure the diameter and multiply this by pi to get a calculated circumference.
Station Five
In this station students work out the minimum amount of wrapping paper required to cover a ball. The focus of the task is on the method used for measurement with students asked to describe their method as well as solve the problem. Copymaster 5 contains student instructions for this activity.
Students need to decide on the shape of the paper they will use. A square is the simplest but they may come up with other options, encourage them as they explore alternatives. If using a square of paper, the circumference of the ball can be used as either the length of the sides of the square, or the diagonal measurement. Using the diagonal measurement will result in less wrapping paper being used.
 |
 |
| Circumference of ball equals diagonal measurement of wrapping paper square. Less paper used. | Circumference of ball equals length of one side of square of wrapping paper. More paper used. |
Measurements will also need to allow for some overlap of paper. Discuss with the students what an appropriate overlap might be.
When students have finished the task have them cut out a piece of paper to the measurements they have worked out and try to wrap the ball. Is it possible? Would they change their answer now they have tried it? If so, what false assumptions were made in the measuring process? Students could make comparisons using the formulae for the surface area of a sphere. S = πd2
This week your child has some measuring to do
- Find a round object at home. You could use the wheel of your bike, the rim of a pot, the edge of a lampshade or anything else you can find.
- Estimate the length around the outside of the circle, this is called the circumference.
- Plan a way to measure the circumference, including the tools you will use.
- Measure the object using your plan. Record your answer.
- Can you think of a way to check your measurement?
| Attachment | Size |
|---|---|
| HowLongisaSlinkyCM1.pdf | 46.82 KB |
| HowLongisaSlinkyCM2.pdf | 40.36 KB |
| HowLongisaSlinkyCM3.pdf | 48.03 KB |
| HowLongisaSlinkyCM4.pdf | 47.25 KB |
| HowLongisaSlinkyCM5.pdf | 48.35 KB |
| HowLongisaSlinkyCM6.pdf | 39.01 KB |
Similar Resources
Around We Go
The measurement of circles and the relationships to be found within them are the focus for this unit. Students investigate a range of circles, each with a different radius, diameter and circumference and assemble this information in their search for relationships.
How Can You Measure This?
In this unit students, working in groups of 2 to 4, carry out and report on a series of investigations involving decisions about how to measure something. The four investigations suggested are:
What’s In a Newspaper?
Students calculate what fraction of a newspaper is devoted to news, sport, advertisements and other categories of information.
Are You a Square?
Students determine whether their height is equal to, greater or less than, the distance from end to end of their outstretched arms.
How Far Do You Walk?
Students work out approximately how far they walk in one year.
How Thick Is It?
Students decide how to measure a length that cannot be measured directly – for example the thickness of a wall of their classroom.
In each investigation the students follow the same sequence:
- Make sure they understand the problem
- Discuss and decide on three different strategies for tackling the problem
- Complete a table to assess the merits of each strategy
- Use the best strategy for conducting the investigation
- Record their methods and results
Giant Mystery
We have the hand print of a Giant…That’s all!! Can we find out how big this giant visitor was? By measuring other people, can we determine the relationship between hand size and body size, to help reconstruct the giant? The unit explores relationships between the hand length, width, span of a person and their height and other body measurements.
Stepping Out
In this unit students find out the length of their pace when walking and running, and compare these with the paces of others
Paper Planes Level 2
This unit is the first of two around making paper planes. In this unit students investigate a variety of designs for paper airplanes and experiment to see which planes fly the furthest. They measure how far their planes fly using the standard measures of metre and cm, compare results and have a flying competition.
This unit is suitable for students that have had plenty previous experience with non-standard units and have had the concept of standard units introduced. It provides a good context for practising the use of metres and cm’s. In the second unit, Paper Planes L3, students create scatter plots of the distance their planes travel when a variable is changed.
