Demonstration-An Effective Technique In Teaching Biology (jnrlse)

Strengths of Demonstrations

1. 
   Teacher—Student Contact. A student comes in direct contact with an instructor and is able to clarify points missed in lectures (see student response in Table 4). Acquaintance with the students helps the instructor tailor the course to individual needs, giving additional instruction to slower students and leading advanced stu- dents to further inquiry (Fig. 3).
   
2. 
   Peer Interaction. Students learn from discussions with their friends and classmates (Table 4). Generally two to four students work together. Frequently, a teach- er explains a concept to one student, and that student explains it to others. There are three main benefits: the instructor is freed of repetitive explanations, allowing more time for other problems; the student learns the concept more thoroughly because he is teaching it; and
   

Box 1. Written description of graphs and tables presented in Fig. 2

Display 1. Farm Productivity and Energy Crises
Increases in productivity of selected farm products from 1935 to 1967 are shown in Fig. 2A.
Ql. What do you conclude from the graphs in Fig. 2A?
Answer. Ses'eral fold increase in total production of agricultural com- modities.
The increase in total production resulted from an increase in output per unit area. For instance, from 1945 to 1970 mean corn yields increased from 34 bushels ( I bushel = 25.4 kg) per acre (1 acre = 0.405 ha) to 81 bushels per acre or 5,079. 1 kg per ha (Pimental ct a1. , 1975). This 2.4 fold increase in production per acre was due to 3.1 fold increase in energy inputs. An itemized description of energy input for corn produc- tion and output is presented in Fig. 2B.
Q2. What do you conclude from Fig. 2B?
Answer. a) Labour input decreased more than 609c .

2. 
   The energy used for machinery, fuel, fertilizers, drying, electricity, and transportation has increased several fold.
   
3. 
   Insecticides and herbicides were not used in 1945 but since the last 20 years their use has been increasing rapidly.
   

The most radical change was observed in energy efficiency. The yield in corn calories decreased from 3.26 per one fuel kilocalorie input in 1945 to a yield of 2.52 kilocalorie in 1970 (Fig. 2B).
Q3. Why is there a reduction in energy efficiency from 1945 to 1970? Answer. The law of diminishing returns.
Q4. How is the current energy crisis related to the production of corn?
Answer. Fossil fuels are directly or indirectly required for the items of energy input listed in Fig. 2B.



other students learn more quickly because of the peer relationship (Farley and Moore, 1975).

3. 
   Development of Skills and Background Kno wl- edge. Students obtain practice in the interpretation and critical evaluation of data, especially the reading of graphs and tables (Table 4). They become familiar with biological and statistical terminology. An effort is made in the demonstration to improve the student's knowl- edge of natural history—examples used consist of a wide variety of native flora and fauna (Table 4).
   
4. 
   Student Choice. Based on 204 responses, a high proportion of students (85 %) said that the demonstra- tions were useful (Table 4). In the survey, we asked the
   

Table 4. The response of students to the effectiveness of demonstration as a teaching technique



Student response t

Items in questionnaire	Positive	Negative	Knew it already
Demonstrations were useful	85	15	--
Learned to interpret a table or graph	69	--	3 I
Peer interaction	78.5	11.5
Got to know one instructor well	82	18
Clarification of points missed in lectures	76	24

t A total of 204 student responses were obtained.

Fig. 3. A teacher discussing a concept with a student.

students to choose one method: demonstrations, labs, strations are usually supplemented with films or slide or tutorials. A majority (61 %) of the students wanted to synchs with tapes pertaining to the topic and, above all, keep demonstrations, l49o recommended the replacing we hold a round table discussion following each sess- demonstrations with labs, and 259o indicated that sion.
demonstrations be changed to tutorials. Other com-

ments in favor of demonstrations were: stimulates participation, encouragement of personalized instruc- tion, very interesting, visually appealing, large amount of material covered well, can work at own speed, rele- vant examples shown, encourages thinking, and facili- tates outside reading.

Weaknesses of Demonslralions

A small percentage of students (15 No) indicated that the demonstrations were not a useful technique. Reasons given were; charts and graphs hard to under- stand, answers to questions not readily available, boring material, instructor not enthusiastic, vague data, am- biguous questions, repetition of lecture material, not enough guidance, and demonstrations covered too much material.

SUMMARY

“Demonstration” is an effective technique which em- phasizes interaction among students and teachers, and students themselves. Students are induced to think, reason, and argue their viewpoints. They also gain prac- tical experience in interpretation of graphs and tables. This technique combines all the tools of communication emphasized by Postlethwait (1978). We use live or dead plant and animal specimens. We provide the students with a written description of the material presented in graphs, photographs, and tables in a display. Demon-