Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

Designing and evaluating experiments

The experiments in this collection develop skills involved in planning experiments. They contain procedural information needed to carry them out. They also have notes and guidance for extending their scope in order to focus on experimental design and evaluation skills.

Selecting equipment and devising an approach
This group of experiments offers good opportunities for deciding what equipment to use and how to use it, selecting quantities to vary, keep constant and change.

In physics, we suffer from the availability of good instruments. Students can learn more about problems encountered by real physicists from making measurements using limited equipment and techniques. For example, find the density of Plasticine using beakers which have only a 50 ml mark, and 100 g masses. To find the volume, put a lump of Plasticine in beaker (or whatever); to find the mass, compare masses by hand, or make a balance using a ruler. Encourage students to estimate the plus-or-minus in these measurements.

When providing equipment for some experiments you could give students a choice of instruments in different scales. Encourage them to justify their selection.

Evaluating and improving experiments
Many students will be used to evaluating their experimental methods after they have carried out an experiment. Comments such ‘I would have measured it better’ are common but also meaningless. Despite pressures on teaching time, it is worth giving students opportunities to implement improvements for at least some of their experiments.

The experiments listed below can help students understand that any experimental method is an iterative process. They make adaptations in the light of preliminary findings in order to improve on their methods.

Related Guidance