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Water Cycle and Its Phases – Investigation 2 CAP


Water Cycle and Its Phases: Investigation 2 – CAP


In this short CAP, we will address the issue of the importance of water on planet Earth. While we study the Water Cycle and Its Phases, it is a good time to also introduce the concept that life on Earth depends on water. So water is very important. All animals need water to drink, just like we do. Plants not only need water but need sunlight as well. Much later, you will learn and understand how sunlight supports plant growth through a chemical reaction called photosynthesis. For now, however, let’s take this opportunity to do the simplest, yet one of the most important experiments ever performed. We will have your class demonstrate that both water AND sunlight are required for plant growth.


This slide is to simply point out to you that both animals and plants need water to survive. Your teacher might ask you what other ways animals and plants use water. Fish, for example, are animals that must live in water. They even get their oxygen from water and do not breathe with lungs. Some animals, like birds, make their nests near water. Elephants use water to cool off… and so on.


This slide shows the two ingredients required for plant growth – water and sunlight. Plants usually grow in soil that contributes certain nutrients required for growth but are not involved in the actual photosynthesis reaction.


In this simple experiment, your class will test the hypothesis that plants require water and sunlight to grow. One might make a prediction that if plants require both water and sunlight, then we will not be able to grow plants without either sun or water. Plastic cups can be used for pots. However, regardless of what is used for a pot, be sure that there are 12 identical pots. Plant three kidney beans (or other common bean seeds) in a nearly full pot of soil, about 3cm deep.


The “A” and “B” pots will be the ones that get water on a daily basis throughout the experiment. Pots “C” and “D” will never be watered.


Putting pots “A” and “C” by a window will provide them both with sunlight. Pots “B” and “D” should be stored somewhere in the classroom where they can be blocked from sunlight. Each day pots “A” and “B” should be water even though the “B” pots will stay in the dark throughout the experiment.


It will take 2-3 weeks for the plants to sprout – hopefully by the end of the CELL. During the experiment, you and your classmates can discuss what you think will happen in the experiment.