General guidance on teaching practical physics

Demonstration or class experiment?

Teaching Guidance for 11-14 14-16

Physics, more than any other science, can be demonstrated principle after principle by direct and simple experiments. In some cases, it is clear that an experiment should be done either as a demonstration or as a class experiment. But many experiments can be done in either way, each having advantages and disadvantages.

Demonstration experiments can clarify a physical principle or show some interesting application of a principle. Make sure that students in the back row, as well as the front row, can see and hear what is going on. The best demonstration experiments avoid unnecessary detail – students can see and understand the whole working arrangement.

Other reasons for demonstrating experiments include safety reasons, and limited apparatus. Demonstrations can also be used as a part of a revision session or when you want to draw quick comparisons, e.g. looking at the behaviour of water waves and comparing that with light or sound. In a short lesson, there may simply not be time for students to carry out their own investigations, after they have set up and dismantled ripple tanks.

Class experiments give students direct experience of physical phenomena. Just as important, they allow students to practise being scientists: discussing, developing hypotheses, designing experiments, predicting outcomes and returning to fresh hypotheses and more experiments. They develop their powers of observation, thinking and problem-solving. Active learning follows the adage ‘hear and forget, see and remember, do and understand’.

Because some students work more quickly than others do, it is a good idea to give students a series of questions to pursue. With a selection of extra equipment set out cafeteria style, students can then proceed at their own pace. That way all remain engaged and faster students accomplish more.

Through class experiments, students can learn:

how to devise experiments
how to work on their own
how to make mistakes
how to solve practical problems
how to enjoy success
and they learn a little theory too.

Asking questions

Teaching Guidance for 11-14 14-16

Contrary to what is popularly believed, physical phenomena do not in themselves reveal theories. Interpreting what is seen often depends on knowing what you are looking for. There are many examples from the history of science either where a discovery was made as a result of the prepared mind of the scientist or where no progress was possible for a time because of theory-laden observation.

Avoid giving students instructions that tell them what they are going to see. With patience and care, even demonstration experiments can usefully model the questioning process basic to science. Students should have many opportunities for experiencing how a series of fruitful questions leads to understanding. A first question leads to an observation, which in turn provokes a new question, etc. Encourage students to discuss what they see.

This approach does take time, but is far better than simply giving dry answers before there is any grasp of a question. Students like to think for themselves and deserve to enjoy this pleasure. Passive learners are more likely to disengage.

Health and Safety statement

Teaching Guidance for 14-16 16-19

Health and safety in school and college science affects all concerned: teachers and technicians, their employers, students, their parents or guardians, as well as authors and publishers. These guidelines refer to procedures in the United Kingdom. If you are working in another country you may need to make alternative provision.

See the health and safety notes in each experiment. This is general guidance.

Health & safety checking

As part of the reviewing process, the experiments on this website have been checked for health and safety. In particular, we have attempted to ensure that:

all recognized hazards have been identified,
suitable precautions are suggested,
where possible, the procedures are in accordance with commonly adopted model (general) risk assessments,
where model (general) risk assessments are not available, we have done our best to judge the procedures to be satisfactory and of an equivalent standard.

Assumptions

It is assumed that:

the practical work is carried out or supervised by a qualified science teacher with adequate knowledge of physics and the equipment used,
practical work is conducted in a properly equipped and maintained laboratory,
rules for student behaviour are strictly enforced,
equipment is regularly inspected and properly maintained,
with appropriate records are kept,
care is taken with normal laboratory operations such as heating substances and handling heavy objects,
good laboratory practice is observed,
eye protection is worn whenever risk assessments require it,
hand-washing facilities are readily available in the laboratory.

Teachers' and their employers' responsibilities

Under the Health and Safety at Work Act and related Regulations, UK employers are responsible for making a risk assessment before hazardous procedures are undertaken or hazardous materials are used. Teachers are required to co-operate with their employers by complying with such risk assessments. However, teachers should be aware that mistakes can be made and, in any case, different employers adopt different standards.

Therefore, before carrying out any practical activity, teachers should always check that what they are proposing is compatible with their employer’s risk assessments and does not need modification for their particular circumstances. Any rules or restrictions issued by the employer must always be followed, whatever is recommended here. However, far less is banned by employers than is commonly supposed. Be aware that some activities, such as the use of radioactive material, have particular regulations that must be followed.

Reference material

Model (general) risk assessments have been taken from, or are compatible with:

CLEAPSS
ASE Safeguards in the school laboratory 11th edition 2006
ASE Topics in Safety 3rd edition, 2001
ASE Safety reprints, 2006 or later

Procedures

Clearly, you must follow whatever procedures for risk assessment your employers have laid down. As far as we know, almost all the practical work and demonstrations on this website are covered by the model (general) risk assessments detailed in the above publications, and so, in most schools and colleges, you will not need to take further action, other than to consider whether any customisation is necessary for the particular circumstances of your school or class.

Special risk assessments

Only you can know when your school or college needs a special risk assessment. But thereafter, the responsibility for taking all the steps demanded by the regulations lies with your employer.

External websites

The Institute of Physics are not responsible for the content of external websites which may be linked from this website's pages.

Interference

Light, Sound and Waves

Classroom management in semi-darkness

Teaching Guidance for 14-16

There are some experiments which must be done in semi-darkness, for example, optics experiments and ripple tanks. You need to plan carefully for such lessons. Ensure that students are clear about what they need to do during such activities and they are not given unnecessary time. Keep an eye on what is going on in the class, and act quickly to dampen down any inappropriate behaviour before it gets out of hand.

Shadows on the ceiling will reveal movements that are not in your direct line of sight.

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