Though it is not part of the GBE Challenge, we decided to plant the extra seeds the same day as the plants in our growth chamber. The only difference is that these pots were put by the window, and are getting natural light. We have noticed a significant difference between the height of the plants growing in the Growth Chamber and the plants growing in our class but exposed only to sunlight. You can even see the plants in the picture above leaning towards the window. The orientation of a plant or other organism in response to light, either toward the source of light ( positive phototropism ).