1. Circumference & Diameter\
Copy the diagram to the right and use it to do these conversions.
1. 2.5m to cm
cm to mm
m to Km
4. 750m to Km
5. 7.5Km to cm
6. 12m to mm
cm to m

2. Making Tricky Measurements
Starter:
Copy the diagram to the right using a quarter of a page and use it to do these conversions.
1. 2.5m to cm (250)
cm to mm (27.8)
m to Km (3)
4. 750m to Km (0.75)
5. 7.5Km to cm (750000)
6. 12m to mm (12000)
cm to m (0.0231)

3. WALT: use a Bunsen Burner safely
Making Tricky Measurements
Demonstrate a suitable way to accurately measure the length of non-linear and other tricky lines.
Describe the relationship between the diameter and circumference of a spherical object.
Convert between mm, cm, m and km.

4. Find the thickness of a sheet of paper
Discuss what you are going to do with your partner before you begin.
Explain your method in your book.
Write the figure you have gained using the correct prefix.
Write down three other examples of materials whose thickness could be deduced in this way.

5. Circumference & Diameter

6. Aims:
Measure the diameter and circumference of a variety of circular objects and record the results in a table.
Use these measurements to plot a graph of circumference vs. diameter
You have 2 mins with your neighbour to decide how you will record these results - discuss

7. Method (copy this) We can use a piece of string to measure lines which are not straight. By wrapping them around an object we can find its circumference and by measuring from one end to another we can find the diameter. Results
Object
Diameter / mm
Circumference / mm 1 2
Ave

8. Graph Plotting (Things to look out for)
Size of graph greater than half the size of the graph paper.
Labelled axes with both quantity and the unit with sensible scales that increase by even amounts.
Plot with a sharp pencil.
Plot points carefully – use a dot for the point surrounded by a circle.
Line of best fit is normally straight or slightly curved.

9. Conclusions: What do your results and the graph show?
Is there a relationship between the circumference and the diameter? (ie when the circumference doubles what happens to the diameter?)
Now try and calculate the gradient of your graph.

10. And to finish…
These units of length aren’t standard but some people do or have used them…
A beard-second
A smoot
A sheppy
Can you guess what these unit of lengths mean and what their values might be?

11. Homework
Complete the sheet “sweets in a jar”