ABSTRACT This paper makes a case for teacher demonstraticns as a method of implementing indirect practical work for pupils at the high school level. The pupils complete worksheets which are then assessed by the teacher. Laboratory or practical work is regarded as an integral part of science teaching and learning at all levels. The pre-amble to the physical science syllabus at senior secondary level explicitly states that - 'Physical science is an experimental science. The syllahus gives ample scope for experimental work carried out by the pupils themselves.' (TED, 1984: 2-3). Laborator work on an individual basis is preferred. However, the implementation of individual laboratory work is virtually impossible due to large class size; time and time-table constraints; lack of laboratory facilities; lack of services, apparatus and equipment; and dearth of qualified teachers. Group laboratory work (3-5 pupils) may be possible but is not that easy either. Under these difficult circumstances, teacher demonstrations, accompanied by appropriate worksheets, may be the answer (Appendix 1). The pupils observing the various demonstrations are asked to complete the worksheets, which are then marked by the teacher. Invariably, there are limitations to this mode of assessment. The development of laboratory (which is an integral part of practical work) cannot be assessed using worksheets. Concept development and knowledge acquisition can be assessed However, under the prevailing circumstances the method may have some merit. APPENDIX I WORKSHEET Name: ........................................... Standard: ......................................... School: ......................................................................................................
(A) INTRODUCTION 1. Observation 1.1 What do we mean by SCIENTIFIC OBSERVATION? ................................................................................................................. ................................................................................................................. .................................................................................................................
1.2 What are the senses we use for observation? ................................................................................................................. ................................................................................................................. ................................................................................................................. 1.3 What is the percentage contribution made to your knowledge by each of these senses? ................................................................................................................. ................................................................................................................. ................................................................................................................. 1.4 When performing experiments in a laboratory, one either takes .........................................................................................
(ie, gather data - QUANTITATIVE) or makes ...................................................................................................................... (QUALITATIVE). Once this is accomplished the next logical step is to ask questions:............................................................. to reach:................................................................................................................. 2. Candle Experiment 2.1 How many observations can one make of a burning candle in, say, five minutes?............................................................... 2.2 Mention five observations of a burning candle. 2.2.1................................................................................................................. 2.2.2................................................................................................................. 2.2.3................................................................................................................. 2.2.4................................................................................................................. 2.2.5................................................................................................................. 3. 'Magic Stick' 3.1 Observation(s) ................................................................................................................. 3.2 Deductions(s)................................................................................................................... 4. 'Love Meter' 4.1 Observations(s)............................................................................................................... 4.2 Deduction(s)..................................................................................................................... 5. 'Bird Whistler' 5.1 Observation(s).................................................................................................................. 5.2 Deduction(s) ....................................................................................................................
(B) CHEMISTRY EXPERIMENTS (Demonstrations)
| Experiment | Observation(s) | Deduction(s) | Concept(s) | Chemical Equations |
| 1. The 'Blue Bottle' Experiment | ||||
| 2. The 'Rocket' Experiment | ||||
| 3. The 'Retarded Fire' Experiment | ||||
| 4. The'Volcano' Experiment | ||||
| 5. The 'Glow Worm' Experiment | ||||
| 6. The 'Fanta/Coke' Experiment |
(C) APPLICATIONS
1. Give three examples of how you use your senses to observe things in your daily lives. a).................................................................................................................................. b).................................................................................................................................. c)..................................................................................................................................2. Name three careers where observation skill is important and brief!y state why. CAREER HOW IS OBSERVATION SKILL USED? a)...................................................................... .................................................................... b)...................................................................... .................................................................... c)...................................................................... ....................................................................
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