Science process skills/Hypothesizing
Contents
Hypothesizing
| Hypothesis is a temporary solution in the absence of complete evidence. Students generally make explanations basing on preliminary experiences. They may not be able to make broad statements. So when an experience is given the students will give explanations. |
Activity - 1
| I. The teacher takes four beakers with water and
puts two spoons of common salt in beaker – ‘A’, two spoons of sugar in beaker – ‘B’, two spoons of sand in beaker – ‘C’, and two spoons of iron fillings in beaker – ‘D’ and stirs all beakers. The students observe that salt and sugar dissolve in water and sand, iron fillings could not dissolve the students are asked to give explanation why the first two substances dissolved and other substances are not dissolved.
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Assessing Students’ Explanations:
1.Water got some kind of affinity towards salt, sugar and hence they got dissolved in water of beakers ‘A’ and ‘B’, whereas water has no affinity towards iron fillings and sand and hence they remained un-dissolved in beakers ‘C’ and ‘D’ – A grade.
2.Water, sugar and salt are like substances while sand and iron fillings are unlike substances to water, hence sugar and salt dissolved leaving sand and iron fillings – B grade.
3.Students could not give any answer – C grade.
Activity - 2
| II. Teacher shows different objects with wide base, small box, short objects and long objects and makes them to stand on the table. When a jolt is given to the table, it is observed that objects with wide base and short length objects are not much disturbed except slight displacement in their position and other got disturbed in their position and fell down.
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Asseing Students’ Explanation:
1.If the base increases or height decreases things/objects are more stable or stability increases – ‘A’ grade
2.Things with wide base and short length are score stable and others are not much stable – ‘B’ grade
3.Some objects are stable and some objects are not stable – ‘C’ grade
Activity - 3
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III. Providing the same situation as explained above, the teacher accepts the hypothesis that wider base of the object; short length of the increases the stability of the object. Teacher asks the students to give some more reasons for the situation or equivalence.
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Assessing Students' Explanation:
1.Students say that stability of the object is depending upon base area and nearness of centre of gravity of the object to the earth – ‘A’ grade
2.When things are placed on the floor, instead on table, they would not get disturbed – ‘B’ grade
3.Even when jolt is not given to the table objects may fell down – ‘C’ grade
Activity - 4
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IV. Teacher takes three beakers A, B, C and equal amount of water say 100 grams is taken in each beaker. Twenty grams of sugar is added to beaker A, 40 grams of sugar is added to beaker ‘B’ and 60 grams of sugar is added to beaker ‘C’. When all the three beakers are allowed for some time, it is observed that sugar in beaker ‘A; is dissolved completely and sugar in beaker ‘B’ and ‘C’ are not totally dissolved. When stirred it is observed that sugar in beaker ‘B’ dissolved and sugar in beaker ‘C’ remained un-dissolved. When beaker ‘C’ is heated that sugar in ‘C’ also dissolved.
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Now the teacher asks the students to give their reasoning and assess them.
1.Students say that solubility increases with stirring and heating – ‘A’ grade
2.Stirring alone improves solubility of the sugar – ‘B’ grade
3.Solubility does not depend upon temperature – ‘C’ grade
Activity - 5
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V. Teacher explains the lesson of forces and equilibrium. After the lesson, the teacher asks the question. It is observed that it is quite easy to balance a moving bicycle and it is very difficult to balance a bicycle at rest. Why?
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Assessing Studnets' Explanation:
1.When a number of forces acting on an object it is easy to keep it in equilibrium – ‘A’ grade
2.As the moving bicycle is under the influence of centripetal and centrifugal forces, the bicycle is balanced – ‘B’ grade
3.By practice/skill we can balance the bicycle – ‘C’ grade
Activity - 6:
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VI. Children performed Hydrilla experiment and observe the water level in the test tube decreases. 1.Volume of gas and the pressure exerted are inversely proportional. 2.Volume of gas and the pressure exerted are directly proportional. 3.Volume of gas and the pressure have no relation.
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Assessing Studnets' Explanation:==
1.The volume of oxygen released is inversely proportional to the pressure exerted – ‘A’ grade
2.The volume of oxygen released is directly proportional to the pressure exerted – ‘B’ grade
3.The volume of oxygen released is not related to the pressure exerted – ‘C’ grade
OR
1.A child interpreting correct hypothesis along with full additional relevant information – ‘A’ grade
2.A child interpreting the correct hypothesis – ‘B’ grade
3.A child interpreting irrelevant hypothesis – ‘C’ grade
Activity - 7:
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VII. The same Hydrilla experiment with increase in CO2 concentration by adding NaHCO3 while reacting with water throughout these changes. Hypotheses: 1.Adding NaHCO3 altered the rate of oxygen bacteria. 2.The increasing level of oxygen liberated does not remain constant.
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Assessing Students' Explanation
The teacher guides the children by providing opportunity till the end of the concept compensation point.
1.A child who interprets the correct answer with accurate reasoning – ‘A’ grade
2.A child who interprets the correct answer without reasoning – ‘B’ grade
3.A child who interprets inappropriate reply – ‘C’ grade
Activity - 8:
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VIII. Sunlight is essential part of the photosynthesis. Hypotheses: Due to non – availability of sunlight photosynthesis has not taken place.
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Assessing Studnets' Explanation
1.A child who hypothesizes the essentiality of various factors of photosynthesis gradually – ‘A’ grade
2.A child who hypothesizes correct relationship between sunlight and photosynthesis – ‘B’ grade
3.A child who formulate defective hypothesis – ‘C’ grade
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