Assignment #4 Part 1—continued
The student used special filters on light bulbs to create yellow, green, and blue light. All the pots in which he planted the bean seeds were the same size and each pot received the same amount of water and fertilizer. The student also made sure all the pots were at the same temperature and the same distance from the light. By controlling everything that might influence plant growth, the student felt sure the only difference would be the colour of the light.
The student used a metric ruler to measure the bean plants on days 7, 10 and 14, and recorded the average plant height. To get the average growth under each light colour, he measured the height of each of the five plants, added the measurements together, and divided by five.
|
Height in millimetres (mm)
|
Colour of
Light |
Day 0
(1st day)
|
Day 7
|
Day 10
|
Day 14
|
| Natural |
0
|
6
|
8
|
10
|
| Yellow |
0
|
6
|
7
|
8
|
| Green |
0
|
4
|
4
|
5
|
| Blue |
0
|
5
|
8
|
9
|
From this data, the student made the following conclusions: "My hypothesis that bean plants grow best under yellow light was not supported." Other conclusions the student made were: "Natural light seemed to be best for the growing flowers, then blue light, then yellow light, and finally green light." A question raised by his teacher was, “As natural light is sunlight, then perhaps your experiment has shown that sunlight isn’t yellow”. Sounds like the student now had a whole new experiment to design!
continued on following page
