Science process skills/Interpreting
I. teacher motivates the class by discussing some situation regarding radiation of heat and how bodies are heated and generates the following questions.
1. Do all the bodies absorb heat equally? 2. Do you feel any difference when you wear a black shirt and white shirt during summer days? If so why? 3. Do all the colored bodies absorb heat equally?
After thorough discussion, the following hypothesis is made.
‘Black bodies absorb more heat than white bodies”.
Take two tins of equal size A and B coated with black paint and white paint respectively. Equal quantity of water is taken in both tins. Both the tins are exposed to sunlight for definite time. The temperature of water in both tins are measured and it is observed that the temperature of water in tin ‘A’, which is colored in black is higher than the other in tin ‘B’, then it is proved that BLACK BODY absorbs more heat than white body. Teacher asks the students what do you say about our initial questions now?
1. If he/she answers the initial questions with the help of the results obtained with explanation – ‘A’ grade 2. If he/she answers the questions satisfactorily but without referring to the results – ‘B’ grade 3. If he/she cannot answer the questions – ‘C’ grade
1) For the first question do all the bodies absorb heat equally, if student answers ‘no all bodies do not absorb heat equally since we got black bodies absorb heat more than white bodies’ – ‘A’ grade 2) ‘All bodies do not absorb heat equally – ‘B’ grade 3) Any other wrong answer – ‘C’ grade
Compare and verify their earlier findings with earlier predictions.
Teacher: The teacher asks the students to predict what happened to the period of oscillation when the length of the pendulum increases?
Student: The students predict that the time period increases/decreases/does not change
II. The teacher shows simple pendulum with some length and asks the student to measure its period of oscillation. Figure:
Now the teacher increases the length of the pendulum and asks the students to find out its oscillation time again and he/she repeats the experiment.
S.No. Length of the pendulum Time for 20 Oscillations Time for one Oscillation L/T2 1. 25 20 1 sec 25 2. 36 24 1.2 sec 25 3. 49 28 1.4 sec 25
Teacher asks the students how are your predictions in the light of your observations?
1) Period of oscillation increased - ‘A’ grade 2) Period of oscillation decreases/no change – ‘B’ grade 3) If he/she fails to tell any answer – ‘C’ grade
III. Teacher shows a double convex lens to the student and asks the student to predict what happens when beam of parallel rays from hot sum are focused on a piece of paper.
Burning paper by converging rays of light during hot sun, teacher asks students ‘What is your prediction now?’
1) The rays of light converged at the focal point of the lens and burnt the paper. Hence the prediction is correct – ‘A’ grade 2) The student says that the paper is burnt and my prediction is correct – ‘B’ grade 3) My prediction is right/wrong (failed to interpret the activity) – ‘C’ grade
Interpreting the various observations made during photo-synthetic activity. Photosynthesis is a process of food production in green plants. Carbondioxide, water are fixed in the plant cell as carbohydrates using the energy derived from sunlight. The three variables that are required for photosynthesis can be summarized as CO2, water and light. Along with the three variables there is an essential component in the green plant is called the chlorophyll (the green color pigment which is present in all green plants).
IV. Teacher performs hydrilla experiment and ask the students to observe the phenomena of photosynthesis.
The observations are recorded in the following table.
S.No. Number of air bubbles Time duration in minutes Under different wavelengths CO2 Conc. Pond/Tap water Different intensities of light Blue (B) Red (R) Green (G) 1. 2. 3. 4. 5.
What do you observe when the intensity of light is changed in a day? Students interpret the results with the help of a graph given below.
1. Rate of photosynthesis increases as the intensity of light increases – ‘A’ grade 2. Rate of photosynthesis decreases with rate of intensity of light – ‘B’ grade 3. Rate of intensity does not have effect on photosynthesis – ‘C’ grade
V. The same experiment is repeated with another variation like using different colored bulbs (colors may be changed by using different colored polythene papers, i.e. red, blue and green).
What difference do you observe in the rate of photosynthesis in three different colored bulbs? Interpret the results you observed in the experiment.
1. Maximum rate of photosynthesis is observed under blue color and least under red color – ‘A’ grade 2. Maximum is under red color and least in blue color – ‘C’ grade 3. Medium rate of photosynthesis under green color – ‘B’ grade
The above interpretations can be proved by taking any other plant and repeating the experiment (e.g. Vallisneria or Convulvulus mesophyte).
Note: In the initial stage, teacher and students arrive at a conclusion from their discussions that the rate of photosynthesis varies under different intensities of light and different wavelengths of light and CO2 concentrations. The interpretations in above events are arrived at by comparing the results obtained and the initial conclusions.