The Curiosity Project
STEMingBoredom 24: grow your own mung beans
This experiment could be done with anything that can be grown, but for two reasons we chose mung beans; first, they germinate quite quickly –growing an oak tree would require the experiment to hold your attention for anything up to 400 years, potentially quite difficult. Secondly, growing mung beans gives you something to eat at the end of the experiment!
Growing anything from seed is known, in the early stages, as germination. It’s the plant equivalent of a chick breaking out of its eggshell. Plants are pretty incredible at what they do – if you keep your eyes open you’ll find plants in all kinds of unexpected places – and nobody put them there to grow, the seeds will just have blown there, or been dropped by a bird or an animal.
But we can take most of the chance out of this and give plants the best possibility of growing by providing them the best environment in which to grow. Doing this can speed up the growing process and also give each seed the best chance of growing.
How to do it:
This experiment is classic: it will have a control. That means that you’ll do two experiments at one time and compare one to the other – one will have what we know to be ideal conditions and the other will have less ideal conditions. From the results, you’ll be able to work out what factors influence growth.
Two jam jars or similar
A clear bowl
First, rinse the beans until the water runs clear, you can do this in the bowl or, if you have one a colander. This cleans the beans of anything that could stop them germinating, or be unpleasant to eat.
Put your beans in a clean, clear bowl. Add in cold water – enough to cover the beans so that they are completely submerged. Soak the beans for 6-12 hours – this may mean (especially in the summer weather) that you have to add more water to keep all of the beans submerged. The beans will swell in size.
Drain the excess water and then rinse the beans with running cold water to get rid of anything that has become dislodged since they swelled. Get some of your kitchen roll, screw it up into a loose ball and place it into each of the jam jars and then dampen it. It should be damp, not sitting in water. You won’t need to put the lid on the jam jar (bowls, or even mugs could be used for this, too).
Sprinkle some of the beans onto the kitchen roll, remembering to give them enough room to expand as they grow.
Take one of the jam jars and put it onto a windowsill that gets direct sunlight. Place the other in a cool, dark place – the bottom of a cupboard would be ideal.
You’ll have to go through a cycle of rinsing the beans, adding water to the kitchen roll and maybe replacing the kitchen roll every so often, so that it stays damp and clean. The process can take 2-5 days.
When the beans have sprouted (or maybe one set have...) take notes which have germinated better and what size they have become in the time you’ve given them. You’ll be able to use this evidence to draw some conclusions about which conditions the beans like the most, and why! PS, the beans are now ready to eat!
Repeat the experiment with three jam jars. Put one jam jar in a cupboard that is dark, one in the fridge and one in the freezer. What are the differences in growth? If they are all dark, what factor is changing their growth rates?