Borrett Rulers

Introduction

In this activity, you will need a normal ruler as well as a Borrett ruler (see below - PRINT ME)!

Borrett Rulers - Rulers.pdf

With your normal ruler, measure accurately in cm 5-10 different items and record your results in a table.

Now, with your Borrett ruler, measure accurately in borretts the same 5-10 items and record your results in a table.


How many cms is 1 Borrett? How do you find this out?

A good strategy is to plot a graph

  • What should all the points join up to form? What if one isn't? Does this mean there is an error?

  • How do we identify the where the mistake is?

  • Why aren't they in an exact straight line?

  • What is the connection between centimetres and Borretts?

  • How do we convert lengths given in one unit to lengths in the other unit?

  • Can the line be extended beyond the scope of the graph?


Further Questions:

  • How long is 45cm in Borretts?

  • How long is 65 Borretts in centimetres?

  • How long is 80 cm in Borretts?

    • How did you get the answer? Why can we do this? What could we not do this for?

  • What is the conversion rule for cm and Borretts? Do these methods always work?

  • Which scales might not have a “ratio” relationship?

  • What is the connection between centimetres and the new unit? Can it be expressed algebraically?

  • What is 1 cm in Borretts? What is 1 Borrett in centimetres?

  • What is 10cm? What is 100cm? What is 0cm?

Further Practice

Some of the essential skills introduced in this lesson are exchange rate and conversion graph. The relevant skills can be found on DrFrostMaths, CorbettMaths, MyiMaths and Eedi. Watch any video and/or go through any online lesson as you see fit.


Transum

  • Currency Conversion: Test your ability to convert from one currency to another with this self marking quiz.

Extension

Draw and use other conversion graphs for commonly used conversions such as:

  • Kilometres to miles;

  • Centimetres to inches;

  • Kilograms to pounds;

  • Litres to pints;

  • Litres to gallons;

  • Celsius to Fahrenheit (not direct proportion).


You may wish to take a look at some of the following Desmos activities:

Exchange Rate - where you will strengthen their understanding of multiple representations of ratios through the context of currency exchange.

The Running Game - where you will use proportional reasoning to predict how long it will take someone to run seven miles. You will also consider the meaning of several graph features in context.


Have a go at the following tasks on conversion:

Conversion Graphs - The Dragon's Back.pdf
Conversion Graphs - Feeling Hot.pdf
Conversion Graphs - Text Me.pdf
Conversion Graphs - Home, Sweet Home.pdf
Conversion Graphs - Money, Money, Money.pdf
Conversion Graphs - Extension Task Sheets.pdf