Measurements and uncertainties

What you'll learn

1. 1

   Imagine measuring a table with a wooden ruler that has seen better days — the end is chipped off! Every measurement has a little wobble of doubt called 'uncertainty'.

2. 2

   If your ruler is chipped at the end, what happens to your measurement?

3. 3

   Drag the ruler to measure the pencil. See how the reading could be 12.3 cm or 12.4 cm? That gap is the uncertainty.

4. 4

   Let's find the uncertainty when you measure a book's width with a ruler marked in mm.

5. 5

   A ruler has mm marks. What is the uncertainty?

6. 6

   Now you try! Measure the length of this line using the mm ruler. Type your answer with the correct uncertainty.

7. 7

   If you measure 4.6 cm with a mm ruler, how should you write it?