Name _______________________________ Date_____________


Growing Sponge animals can be bought at toy stores. The newest growing insects batch did not work very well, I suspect they changed the formula

The teacher's guide has alternatives


Sponge Animals

Materials: Growing Animals (toys), ruler, water, warm water, tweezers

Question: How does water temperature affect the rate of growth of a sponge animal?

To answer this question, you will need to gather data as your "animal" grows and plot its size on a line graph.

Experiment Design:

1.   Measure the length and weight of the insects at start time (Time 0)

2. Place one object in room temperature water, and the other object in warm water.

3. Measure the length of the insects in cm as they grow (approximately every 5 minutes) and weigh the insects at 15 min, 30 min and then on the following day.

Make a Prediction: Which insect will grow faster, the one in warm water or the one in room temperature water?

Data Table

Object 1 (length) Object 2 (length) Object 1 Object 2
Time (min) Room Temperature Warm Water Room Temp Warm Water
0 (start) Starting Weight
15 Weight After 15 Min
30 Weight After 30 min
40 Weight After 1 Day


Graph TWO LINES on the grid below. Place time on the X axis and length on the Y axis.



1. Why was it important to choose the same type of insect for growing?

2. Which type of water made the insect grow faster? How do you know this for sure?

3. Examine this graph of worms as they grow. Assume that length is measured in centimeters.


A) Which worm had the fastest rate of growth? ______ Which worm had a constant rate of growth? ______

B) How big was worm A on Day 15 ? _____ How big was worm B on the same Day? _____

C) How big were both worms on day 25? _______

4. Growth rate can be measured by calculating he SLOPE of a line on a graph. To calcuate the slope, you need to pick two points on the line. Let's use WORM B to calculate a slope (m).


What is the slope of WORM B's Line (show work above)? _____________

5. Once you have the slope (m) calculated, you can create an equation that can be used to PREDICT growth patterns.The equation for a line is

y = mx + b

m = the slope (you calculated in #4)
b = the point where the line crosses the Y axis, in our worm's case, b = 22

Write the full equation, plugging in the numbers for m and for b: __________________________________

6. Now that you have the EQUATION, you can use it to calculate how big your worm will be in on DAY 30.

Show calcuations and answer:



7. The same number can also be estimated by extending the LINE out to Day 30 and using the graph. Show on the worm graph above where worm b's line would be on day 30 (assuming its growth remained constant).

worm8. How big will your worm be on Day 500 (assuming a constant rate of growth)?

Show your calculations and answer:



Is this a realistic number? Why or why not?