Keeping a record of practical work

Keeping a record of practical work

During an investigation records should not be made on odd scraps of paper, but in a laboratory or field notebook. Like a diary, this is a permanent record of what is done each day (for example, of the amount of each ingredient in any mixture, the methods used in all preparations, the arrangements for the standardisation of the conditions for each investigation, the instrument numbers, the temperature and atmospheric pressure if these are relevant, and any safety precautions).

The organisation of numerical data should start as they are recorded, on carefully prepared data sheets. These tables should be pages in the notebook, or they should be securely fixed to the appropriate page. The first column of each table (the stub) may have a heading Date or Time and each of the other columns must have a heading to indicate what was observed or measured each time entries were made, and the units of measurement (see page 93). Preparing a data sheet, when the work is planned, helps you to decide what is to be recorded. During the investigation, a data sheet is an aid to observation. It directs attention to the readings required, helping to ensure that data are recorded in order and at the right time so that a complete record is kept. Then, after the investigation, because the data are neatly arranged, the data sheet facilitates the perusal and analysis of data to derive the results that may be included in your report of the work.

Your notebook is also the place for a drawing of the apparatus, for circuit diagrams, and for line drawings made as records of observations. These should be completed in the class (on unlined paper) and should include a scale bar– as on a map. Notes are normally required to supplement the drawings: the practical class being an opportunity to observe, think, select, record, learn and remember, not an art lesson. Together, a student’s drawings and notes should be useful for reference and for revision prior to tests and examinations.

Laboratory and field notes should not be made in rough and copied later. This wastes time and mistakes may be made in copying. It is best to make neat records and to write in carefully constructed sentences. Every note should be dated. The date cannot always be remembered and it may assume great importance later, indicating the order in which things were done. The date is also the key to records made at the same time by other people, of such things as weather, day-length and the state of the tides. For the same reasons, keep a record of the starting time, of the time when each note is made during an observation, and of the time the observation ends.

Details such as these will be required if the work is to be repeated and for the Materials and Methods and Results sections of a report, and should not be trusted to the memory. It may not be possible to write your report if some

detail has not been recorded. Things which seem unimportant during an investigation may prove to be important later. A laboratory notebook should then provide the information about why, how and when, observations were made. A field notebook should provide a similar record not only of why, how and when, but also of where observations were made. If data recorded in a notebook are copied into a computer file, there is a possibility that mistakes will be made in copying. The notebook containing the original data should not, therefore, be discarded: it should be stored in a safe place.

The report on any investigation, whether this is a class exercise completed in one afternoon by a student or several months’ work in an industrial or research laboratory, must be based on records prepared during the investigation. It will be easier to write the Introduction and Discussion sections of the report if the reasons for starting the work, and notes on the development of arguments and hypotheses, are recorded during the investigation.

The use of a bound notebook, with each page dated and with times recorded, helps to ensure that all notes are in chronological order. If looseleaf notes become disarranged, and each page does not include dates and times, it may not be possible to put them together again in the correct order, or if a notebook is lost during an investigation that has taken weeks, months or years, much time and money has been wasted. Research students and working scientists are therefore advised to use a bound notebook and to keep a photocopy or carbon copy of each page on loose-leaf in another place. Carbon copies have the advantage that they can be made anywhere, as notes are made (at any time). Similarly, back-up copies of computer files should be kept in another place (see page 190). Those who fail to take these basic precautions may lose irreplaceable notes (see Figure 2.1). Such losses, which are never expected, may result, for example, from fire, flood or theft, losing luggage on a journey, or the accidental deletion of computer files.

In work requiring special equipment or facilities do not dismantle the apparatus until your observations have been completed, your data analysed and the first draft of your report written, so that if necessary, you can make further observations at any stage during the work.

In any investigation it is very important to record observations that are not expected, because it is from these and from experiments that go wrong that we may learn most. In his Life and Letters, Charles Darwin (1809–82) wrote:

I had also, during many years followed a golden rule, namely, that whenever a published record, new observation or thought came across me, which was opposed to my general results, to make a memorandum of it without fail and at once; for I had found by experience that such facts and thoughts were far more apt to escape from memory than favourable ones.

Figure 2.1 Keep a carbon copy of each page of your notebook in a safe place.

It is worth remembering that many discoveries are made as a result of unexpected observations in experiments designed for some other purpose (see Beveridge, 1968). This is because we can make plans only on the basis of existing knowledge– our previous experience. We can recognise problems, speculate, investigate, formulate hypotheses, and test hypotheses by experiment, but we cannot plan for something that could not have been foreseen.

Students are advised to devote their time in laboratory or field work to: (a) thinking about the reason for the investigation; (b) completing the necessary practical work; (c) recording observations (data) and analysing data; and (d) making notes for possible inclusion in the Discussion section of a report. In other words, each practical class should be used as an opportunity to observe, think and learn. So far as possible, the work should be completed in class. Additional notes may be made after the class, but these should be clearly distinguishable from records made during the investigation, as should amendments to lecture notes made in the light of personal observations recorded during practical work.