Science experiment to investigate the living conditions of algae

What do living organisms like algae need to grow?

We decided that algae needs air (or carbon dioxide), sunlight which is their food, nutrients from the water and warmth.

As a class we started an experiment to investigate the conditions that algae needs, and what would happen if they were missing any of these things.

We took some pond water and placed it into 4 containers. We put nutrients (or fish food) into some of the pond water. We decided to create these four experiments:

Sun and no food  /  no sun and no food /  sun and food /   no sun and food

Before the experiment, the pond water was still quite clear with some green in it. Here you can see the nutrients in the pond water (5 fish food pellets)

We predicted what we think will happen to all 4 experiments, after a week in these conditions. Some children thought the colour of the water might change whilst some thought something might grow in some of the containers.

So what is the effect of sunlight on plants? We covered up 2 leaves on some of the flowers, on this plant. In a weeks’ time, we will see if there are any changes. Some children predicted that the covered areas will change colour, or die.

After the half term, most of the water had evaporated, except for the pots that were covered with tin foil.

The pot that contained food (nutrients) but had no sun was growing something!! We guessed it may be macro algae, as we did start with pond water with lots of micro algae in it. This is what it looked like.