Page 314 - New Medley 5 Semester 1

STEM ACTIVITY 3

Testing for the presence of fat in groundnut
¶ Take a white sheet of paper.
¶ Place some crushed groundnuts in the centre of the paper.
¶ Fold the paper to press the groundnuts gently.
¶ After some time, observe greasy or oily spots on the paper.
¶ These translucent, oily marks indicate the presence of fat in the groundnuts.

STEM ACTIVITY 4

Observing fungal growth on bread
¶ Take a slice of bread.
¶ Sprinkle some water over the bread slice to make it slightly moist.
¶ Place the slice in a dark corner of the room to create a damp, warm environment.
¶ Leave it undisturbed for 2-3 days.
¶ After 2-3 days, use a hand lens to closely observe the surface of the bread slice.
¶ Notice the growth of fuzzy, greenish or blackish patches — these are fungi
(moulds).
¶ Fungi grow in moist and dark places.

STEM ACTIVITY 5

Making a working model of lungs
Remove the bottom of a wide plastic bottle. Make a hole in the cork and insert a Y-shaped glass tube in it. Fix two deflated
balloons to the two free ends of glass tube. Now insert the cork in the mouth of the bottle from inside. Finally attach a
sheet of rubber over the open bottom of the bottle as shown in the figure.
Seal the cork with modelling clay or wax.

Plastic
bottle

Y-tube
Balloons
Volume
(decreases)
Volume
(increases)
Rubber
sheets

Gently pull the rubber sheet down. Observe the change in balloons, which gradually increase in size. Gently release the
rubber sheet and observe what happens.

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