Science process skills/Predicting

Predicting

The teacher describes a situation related “law of floatation” and encourages to answer after visualizing or imagining about the activity and also asks to carry out some simple activities before answering.

Activity - 1:

Activity

I. We are all aware of the fact that a substance which flows from one point to another is called a fluid. Fluid is a common name given to both liquids and gases. Everybody has a certain weight and a certain base area. When a body rests on a surface, it exerts a force equal to its weight, normal to its surface. This total force acting normal to the surface is called “thrust”. Fluid exerts – (1) upward pressure, (2) downward pressure and (3) lateral pressure. Figures:

Assessment

When different substances are dropped in a liquid in a container, it is observed that the substance dropped will try to reach the bottom by virtue of its weight whereas the liquid exerts upward pressure on the sinking body or substance. Teacher describes this situation and then asks what will happen when iron nails, pieces of wood and piece of candle are dropped in a beaker containing water. No prediction (all sinks) – ‘C’ grade Iron nail sinks, wood sinks and candle floats – ‘B’ grade Iron nail sinks and other substances namely wood and a piece of candle floats – ‘A’ grade

Note: If the student predicts that iron nails float or wood sinks, the teacher should provide an occasion to the students to conduct the said activity and correct themselves.

Activity - 2:

Activity

II. When teacher takes three things made of iron only namely, iron nail, bottle lid and a thin iron sheet and all these are dropped in a beaker containing water and asks the following question. What happened to all the three articles when dropped in a beaker of water? All three articles sinks in to the water immediately – ‘C’ grade Nail sinks first; lid sinks slightly after the iron sheet sinks lastly iron sheet sinks – ‘B’ grade

Activity - 3:

Activity

III. When all the three articles are dropped vertically what happens? Iron nail sinks, iron lid floats and iron sheet floats – ‘C’ grade All substances sinks – ‘B’ grade

Activity - 4:

Activity

IV. Teacher presents the graph showing the relationship between temperature and rate of respiration and asks following questions. 1. What happens if the temperature is raised above 400C? No change – ‘C’ grade Rate of respiration increases – ‘B’ grade Rate of respiration decreases – ‘A’ grade 2. What happens to the rate of respiration if the temperature is lowered than 100C? Respiration rate decreases – ‘A’ grade Respiration rate remains same – ‘B’ grade The plant stops respiring – ‘C’ grade

Activity - 5:

Activity

V. Teacher presents/demonstrates the experimental setup as shown in the figure. A B Teacher may give the clue that lime water turns milky when it absorbs CO2

Assessment

1. What change will be observed in the bottles after one/two days? a)Lime water in both the bottles turn milky - ‘B’ grade b)Lime water in bottle ‘A’ turns more milky than in bottle ‘B’’ – ‘A’ grade c)Seeds die due to suffocation – ‘C’ grade 2. What happens if more dry seeds are added to bottle ‘B’ up to its brim? a) More corbondioxide is evolved – ‘B’ grade b)Lime water turns more milky as more CO2 is evolved – ‘A’ grade c)Seeds stop respiring – ‘C’ grade

Activity - 6:

Activity

VI. A beaker full of water is taken and few crystals of KMnO4 are carefully dropped into the water in the beaker. Teacher draws attention of children towards gradual change in water color.

Assessment

When will the whole water becomes uniformly colored? If the child says that – 1.When both water molecules and KMnO4 are in motion – ‘A’ grade 2.When the beaker is kept undisturbed – ‘B’ grade 3.If the solution is stirred well – ‘C’ grade

Activity - 7:

Activity

VII. Chart showing the experimental setup before and after the process of osmosis takes place. Figure:

Assessment

1. What will happen if equal concentrations of solutions are taken in both funnel and beaker? a) Osmosis will not take place – ‘A’ grade b) Level increases in funnel – ‘C’ grade c) The levels in both funnel and beaker may not change – ‘B’ grade

Activity - 8:

Activity

VIII. A farmer provided exactly same conditions for paddy plants using same seeds. There is large number of earthworms in field A than in B.

Assessment

1. Will there be any difference in the yield from these two fields? a) Yes – ‘A’ grade b) No – ‘C’ grade c) May be – ‘B’ grade 2. What difference may be expected? a) More yield from field A – ‘B’ grade b) More yield from field A than in B – ‘A’ grade c) Less yield from field B – ‘C’ grade

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