Page 260 - New Medley 5 Semester 2

 Pour the salt solution into the cup, just enough to cover the sand.
 Leave the mixture to dry undisturbed for 2 to 3 days.
 Once dry, cut open the paper cup and observe the formed rock.
Notice that the salt crystals appear between sand particles.

e salt acts like a cement, holding the sand grains together.
STEM ACTIVITY 4

Exploring the use of ramp
 Place a book at on the surface of a table.

 Now, put a crayon box at one end of the book.
 Use a scale to push the crayon box from one end of the at book to the other.

 en, create a ramp by placing a wooden block under one end of the book to li it.

 Place the same crayon box at the top of the inclined book (ramp).
 Again, use the scale to push the crayon box down the ramp.

 Less e ort is required to push the crayon box down the ramp than on the at surface.

STEM ACTIVITY 5

Creating a model of solar eclipse
 Take a big ball and place it on a table — this represents the earth.
 Take a small ball and tie a sling or string around it — this represents
the moon.
 Suspend the small ball between the torch (sun) and the big ball (earth).
 Keep the torch on the le side of the setup to represent the sun.

 Switch on the torch to shine light towards the earth.
 Carefully adjust the small ball (moon) so that its shadow falls on the
big ball (earth).
 e small ball blocks the light, creating a shadow on the big ball

(earth).

is is how a solar eclipse is caused.
STEM ACTIVITY 6

Making a mini volcano and see how bubbling happens when two substances react
 Make a mound of soil in an open area and
insert an empty coke can in its centre.
 Add two spoonfuls of baking soda into the
can.
 Add about a spoonful of liquid soap.
 Add 5 drops each of red and yellow food
colours.
 Now add about 100 mL of vinegar into the can
and watch what happens.
 Mixing certain substances can create a
zzy eruption just like a volcano giving out

coloured foam from its top.

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