Introduction
Using plastic sheets of different sizes to make a parachute, you can show how the area of a surface affects air drag/resistance and how various objects in nature use this principle to their benefit.
Tools
Video Overview


Cut the bottom of the plastic bag and spread it open.

Cut between the two layers on both sides so as to get two separate pieces of plastic.



Cut a 20 cm x 20 cm square out of one of the plastic sheets using a ruler and cutter.



Take the 20 cm x 20 cm plastic sheet.

Fold AB over CD to make a rectangle.

Now, fold QS over PR to make a square.

Overlap vertex L with vertex O.



We have a right angled triangle ABC.

Fold the side AB towards the hypotenuse AC. Now you get one small and one big triangle.

Cut along the line BQ.



As you open the triangle, you'll find the 8 creases (16 `corners'); here we have marked every alternate crease line to identify 8 evenly spaced locations along the edge of the parachute.

Place eight cotton threads ( 25cm each) at the edge of the creases.

Stick them using a tape.



Bring all the cotton threads together, without tangling them.

Twist them together at their tip.



Insert the threads into the ring magnet.

Make a tight knot.

Repeat all the previous steps to make a parachute of a different size i.e using a 40cm x 40cm plastic sheet.



Hold the parachute as shown in the figure.

Drop the parachutes from a sufficient height (e.g. terrace or balcony of a 1 or 2storey building) and watch them descend!



Release both parachutes from the same height at the same time. Record the time taken by each to touch the ground.

Double the weight on each parachute and measure the time taken to descend the same height.

Measure the surface area (and mass, if possible) of each parachute, and its average velocity in each of the cases.

Use 4 suspension lines instead of 8 and then record the time taken by the parachutes to touch the ground. Compare it with your previous observation.
