ISA and EMPA
Practical skills are assessed by one of two methods:
The Investigative Skills Assessment (ISA) and Practical Skills Assessment (PSA), code PHYA3 (T)
The Externally Marked Practical Assessment (EMPA), code PHYA3 (X).
Most schools and colleges do the ISA, but some do the EMPA. There is no question of advantage or disadvantage for candidates taking either route. The notes that you have been reading are valid for both.
Schools and colleges get the ISA instructions during the Autumn Term. You will do two tasks, P and Q, at times that are appropriate. Some teachers build the activities to the scheme of work. Others may do the ISA straight after the January examinations.
There are two tasks, both of which are marked by your teacher. Your teacher is allowed to tell you the marks, but is NOT allowed to give feedback. The best mark is submitted to the Board. Your teacher is expected to mark the work according to a mark scheme, and cannot deviate from it. Therefore s/he cannot give you marks because you have made a good effort. You may well also do a practice ISA beforehand. Your teacher will give full feedback and support to prepare you for the real thing.
The ISA is a full examination and must be treated as such. Your teacher is allowed to tell you what the ISA task is about, but must not give you any further information. You must not ask for, nor will you be given any further information. A minority of teachers do give clues beyond the limits of what they are allowed. If they get caught, they do make themselves liable to disciplinary action. They can be dismissed for gross professional misconduct. And the school concerned could find themselves being no longer an examination centre.
When you do the ISA, it will be done under examination conditions. This includes the rule about no mobile phones. When you have finished, you must not discuss the exam with your friends. Otherwise this could compromise the security of the examination. And you must NOT go to internet forums and discuss it there. Nor, for that matter, should you read what others say. At best, the material they post may well be rubbish. At worst, you could be considered to have gained an unfair advantage. That could put your exam at risk. So don't.
This is the practical task on which the ISA is based. You will be given a task sheet, with some instructions and a diagram.
You are NOT expected to do a method or a diagram. No marks will be given for this. Instead, do exactly what it says on the sheet.
You may be asked to record the precision of your instruments. Note it down with the units.
You may be asked to set the experiment up (or it could be done for you). If you are unable to set up the experiment, you may ask for the experiment to be set up for you, so that you can, at least, harvest data. You will lose any marks for setting up the experiment.
Do the experiment as instructed on the sheet.
Your data should be recorded on a table, including repeats.
Your data must be recorded to the precision of the instruments. The averages from repeat readings must be recorded to the same number of significant figures as the data.
If you process data, the number of significant figures must be no more than the minimum number of significant figures.
When you draw the graph, remember the rules. Graphs should always:
Be large Ė they should occupy the whole of a side of A4 paper.
Have a title to tell the reader what the graph is about;
Have sensible calibration of axis, with simple scales;
Have both axes labelled with the quantity and units.
And do them in pencil, please.
Section A consists of Question 1.
In this part of the exam, you will be asked some general questions on the data that you have collected. You will also be asked a question that is likely to involve working on the gradient of your graph.
You will be asked about the precision and range of your results. You will be also asked about errors (or uncertainties). Follow the guidance in these notes.
Here you are given data that are derived from an experiment similar to what you did. You will be asked to do the following:
Complete a table.
Take some averages
Plot your data to complete a graph
Take the gradient of the graph.
Process the gradient to get a constant.
Consider the reliability and validity of the data.
Design a further investigation
Question 2 has data that have been harvested from an experiment that is the same (or very similar) to the one that you have done.
You will be asked to complete a table. As well as getting the numbers right, you must pay attention to significant figures. The data above will give you clues. If the data are to 3 significant figures, you answer to three significant figures.
If there are data to 2 significant figures that you have to use for a calculation, then that answer should be to 2 significant figures.
Then you have to plot your data points onto a graph, onto which other data have been already plotted. And you have to draw a line of best fit.
Then you take the gradient. Large triangle, at least 8 cm. Calculate the gradient and give your answer with the units (this might be a separate part to the question).
There may be a question on the uncertainty. Make sure that you read the question to see if itís an absolute error. If it is, add the units.
In this question, you look at the reliability of the data. You may be asked about the sources of error. In timing experiments, reaction time is the most obvious one. You then will be asked to quantify the errors.
Then turn the errors into a percentage, if you are asked to combine the total error. Errors add up. When you have your final error, you may need to convert it into the error in the final answer. In which case, include the units.
You will be asked about what kind of error this is. Mostly it will be random, although if they say something about a piece of apparatus, then it could be a systematic error.
Never use the term human error; itís too vague.
Remember that data are made reliable by doing repeats. They are valid if they are relevant.
This question gets you to plan a further investigation that addresses some other aspect related to the experiment that you have done.
Read the question and answer it.
Your answer should be written in the form of a set of instructions to another student who missed that lesson and wants to catch up.
If you are asked to write about an experiment, you must include the following:
A set of instructions;
Ranges of instruments;
How to make the data reliable.
Many students lose marks on this bit, because they go into the theory. They have a splendid answer to another question. Unless it tells you to do this, donít do it.
Clearly these notes will not catch every eventuality, but if you put them into practice, the ISA and its exam should be marks for the taking.
The AQA will send details of 5 practical activities that students will have to do throughout the year. Although no marks are used by the Board, your school will have to confirm that the candidates have done the activities. Your teachers may well mark the work and give a score for their own monitoring of your progression.
The EMPA itself consists of:
Two related tasks with specific instructions. The way the tasks are carried out are quite like the traditional practical examination. There are specific questions that you will need to answer as you do the practical.
An examination of similar form to the ISA (see notes above).
The Board will send details of the task to your school or college in March, so that the EMPA is done during the first half of the Summer Term. You will do the tasks and the examinations at specific dates as determined by your Physics department.
Your teachers will not mark the paper; the papers are sent to an examiner (an experienced teacher at another school in another area). You will get the results in August.
The EMPA is a full examination and must be treated as such. Your teacher is allowed to tell you what the EMPA task is about, but must not give you any further information. You must not ask for, nor will you be given any further information. A minority of teachers do give clues beyond the limits of what they are allowed. If they get caught, they do make themselves liable to disciplinary action. They can be dismissed for gross professional misconduct. And the school concerned could find themselves being no longer an examination centre.
When you do the EMPA, it will be done under examination conditions. This includes the rule about no mobile phones. When you have finished, you must not discuss the exam with your friends. Otherwise this could compromise the security of the examination. And you must NOT go to internet forums and discuss it there. Nor, for that matter, should you read what others say. At best, the material they post may well be rubbish. At worst, you could be considered to have gained an unfair advantage. That could put your exam at risk. So don't.