How can you measure the rate of growth?

I have a science experiment, and I can%26#039;t find out how to measure the rate of growth without disturbing it.

Info on my experiment:

Title: The effect of the Type of light on the rate of growth of rock candy

Hypothesis: If there is no light, than the rock candy will grow faster.

Independant variable: Type of light

Levals of the IV: Sun light | None | Fluorescent Light | Desk Lamp

Repeated trials: 3

Dependant Variable: rate of growth of rock candy in cenimeters

Constants:

Tap water- 1800 mL

Sugar- 3600 mL

Washers

Strings- 11 cm

Pencils

Snapple jars

Balance

Time: 2 weeks

Graduated cylinder

Marker

Room temperature

Step 1:Measure 450 mL of water, 900 mL of sugar, and cut out 11 cm of string.

Step 2:Heat water until it閳ユ獨 boiling.

Step 3:Add the sugar, and then stir with a wooden spoon.

How can you measure the rate of growth?

So.. you can%26#039;t figure out how to measure the mass each day without distubing it.

I know how.....

For each type of light, make 7 jars. (or 5 jars to be easier.)

Every other day, disturb one jar, and measure the mass of rock candy. Meanwhile the other jars are UNdisturbed and continue to grow under the same conditions. (5 jars? disturb one jar every 3 days) 3-6-9-12-14 days.

Then, at the end of two weeks = 14 days, you will have measured 7 (or 5) pieces of UNdisturbed rock candies, all growing under the same conditions and the same light.

Graph your data for each %26quot;type%26quot; of light. Not for each jar, because you keep disturbing the jars.

For each type of light, that is (sun, none, flourescent, incandesent).

My guess is that the growth will speed up as the surface area of the crystal increases. The sugar crystalizes on a sugar surface. As the surface gets bigger... the crystal grows faster. A graph with a curved line....upwards through time.

Save all the rock candy and sell it to your classmates. Science PAYS off, ha ha.