A drawing sheet changes when you draw a picture on it. Can you reverse this change?
No, we cannot reverse this change if the picture drawn on a drawing sheet with colours. But we can reverse it, if the picture is drawn by a pencil, then by erasing it we can reverse the change.
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?
Give examples to explain the difference between changes that can or cannot be reversed.
Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
S.No. | Change | Can be reversed (Yes/ No) |
---|---|---|
1 | The sawing of a piece of wood | |
2 | The melting of ice candy | |
3 | Dissolving sugar in water | |
4 | The cooking of food | |
5 | The ripening of a mango | |
6 | Souring of milk |
(a) Which kind of garbage is not converted into compost by the redworms?
(b) Have you seen any other organism besides redworms, in your pit? If yes, try to find out their names. Draw pictures of these.
Rearrange the boxes given below to make a sentence that helps us understand opaque objects.
Do you find that all living beings need the same kind of food?
Name the major nutrients in our food.
Classify the following fibres as natural or synthetic:
nylon, wool, cotton, silk, polyester, jute
Name five objects which can be made from wood.
Why do we need to separate different components of a mixture? Give two examples.
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal.
Fill in the blanks:
(a) Joints of the bones help in the ——————— of the body.
(b) A combination of bones and cartilages forms the _______ of the body.
(c) The bones at the elbow are joined by a ______________________ joint.
(d) The contraction of the _____________ pulls the bones during movement.
What is a habitat?
Write the similarities and differences between the motion of a bicycle and a ceiling fan that has been switched on.
Do you find that all living beings need the same kind of food?
Why can a pace or a footstep not be used as a standard unit of length?
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal.
Fill in the blanks in the following
(i) Artificial magnets are made in different shapes such as __________, __________ and ____________.
(ii) The Materials which are attracted towards a magnet are called________.
(iii) Paper is not a ______ material.
(iv) In olden days, sailors used to find direction by suspending a piece of ___________.
(v) A magnet always has __________ poles.
Fill up the blanks
(a) The presence of specific features, which enable a plant or an animal to live in a particular habitat, is called .
(b) The habitats of the plants and animals that live on land are called habitat.
(c) The habitats of plants and animals that live in water are called habitat.
(d) Soil, water and air are the ———— factors of a habitat.
(e) Changes in our surroundings that make us respond to them, are called .
Explain the process of making yarn from fibre.
Fill up the blanks in the following:
(a) The process of changing of water into its vapour is called _________________.
(b) The process of changing water vapour into water is called _________________.
(c) No rainfall for a year or more may lead to _________________ in that region.
(d) Excessive rains may cause _________________.
Name the part of the plant which produces its food. Name this process.
How are cactus adapted to survive in a desert?