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Lesson 2: Using a Ruler to Measure Length

Brain Teaser!

Let’s get our brains warmed up! Complete the challenge below, using informal units of measurement. What did you discover?


Yesterday, we looked at informal methods of measuring length. Talk to your grown up about how you found it.  Was there anything you found challenging? If your grown up cannot help you, write down what you found difficult and talk to your teacher about it when they call in the week.


Today we are going to learn about formal methods of measuring length and learn how to use a ruler correctly. How do we use a ruler? What do the numbers and the lines represent? When do we use a ruler? What does cm and mm stand for? What number do you start on? Where do you place the ruler?


Below is a PowerPoint and YouTube clip on how to ensure you are using a metric ruler correctly and accurately.

Tutorial: How to use a metric ruler


Now that you’re confident to using a ruler to measure length, we would like you to walk around your home and find at least 5 objects or more to measure using a ruler.

Convert the the objects you have measured from centimetres into millimetres.



If you do not have a ruler, please don’t worry there is a printable one at the bottom of this page.


We would like you to complete this table smiley



Length of object in centimetres



e.g. book