Worksheets and ideas to get students thinking about accuracy and prevision in science (GCSE and Key Stage 3)
I used to get very confused over the terms accurate and precise. Accurate results are results that are close to the true value. In science we rarely know what the true value is so this can be quite a difficult concept to master.
Precision is not really about decimal places – instead if refers to the closeness of two or more measurements to each other. Obviously, if you are recording results to more decimal places (sig figs) then they could be more precise than recording to one e.g. 12.5 and 12.6 are more precise results than 12 and 12. But, 13 and 17 are more precise than 13.5 and 20.5.
A good analogy to help understand accuracy and precision is below.
Imagine a basketball player shooting baskets. If the player shoots with accuracy, his aim will always take the ball close to or into the basket. If the player shoots with precision, his aim will always take the ball to the same location which may or may not be close to the basket. A good player will be both accurate and precise by shooting the ball the same way each time and each time making it in the basket. Source
GSCE and Key Stage 3 worksheet on accuracy and precision. Students work through a problem to see if they understand the difference between the terms accuracy, precision, reproducibility and repeatability. (PDF)