Using significant figures

Mathematicians are quite happy to talk about exact numbers however big or small, but in Science a measurement stated as part of the results of a scientific experiment can NEVER be exact. In experimental work across all of the three science subjects, students will be expected to take measurements and record data that is appropriate to the context and apparatus used. The use of digital dataloggers and the processing of data such as the calculation of averages can lead to some common errors with inappropriate use of significant figures. This can also be compounded by challenges with their appreciation of the ideas around accuracy and precision.

It would not be unusual to see a student to produce a results table that contains three time readings of 2.5s, 2.6s and 2.8s and then an average time of 2.63333s without any awareness of the implication of the increased number of significant figures in the average figure provided.

In the mathematics classroom student will meet decimal places but this not be what is most useful in terms of scientific accuracy. In Science significant figure are used to more correctly state the accuracy of a result. If this difference is not discussed with students it may cause misunderstanding to develop. 

Make sure students do not drop zeros and hence the place value of the digits. For example 78602 to 2 significant figures is 79000 NOT 79. If this is a problem discuss the role of 0 as a place holder. Again using significant figures in the context of the Science classroom gives them the opportunity to discuss the “sense” of their answer based on its magnitude.

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