CLASS: 1st – 5th 30 mins SESE (SCIENCE)
- Biology - Nature
- Physics - Shapes and stability
Learning Objectives - WALT (We are learning to…)
- Understanding eggs and their shape
- Learning about stability in shapes and weight distribution
- Structures in Nature and their uses
- Talk and Discussion - listening, questioning
- Active Learning – Hands on learning experience with real life examples.
- Skills through Content: observing, predicting, describing, experimenting, reflecting
When we look at an egg, we notice it has a very special shape! While we normally consider eggs to be weak and fragile, the unique shape actually makes it very strong in certain ways. This is why the egg doesn't break when a bird is sitting on it.
The egg is very strong along its length, while quite weak along the shorter part across. This is because of the dome shape at the top and the bottom of the egg. Can you think of anywhere else in nature and the real world you would find this shape? Use the internet and books to find things that have this similar dome structure.
For the first part of this experiment, we are going to test one eggs strength. Take one egg and rest the bottom part of it in the palm of your hand, carefully rest your middle finder on the top part of the egg and squeeze! You won't be able to crack the egg! If you are afraid the egg may break, you can wrap in in some cling film.
Since the egg is very strong in this direction it will not crack, however if we switch the direction and squeeze the egg from the sides it will as it is weak in this direction.
Let us take a closer look at this shape. The reason a dome is so strong is because it spreads the weight around. We see this shape in nature in things like turtle shells, eggs and beehives. These all help protect the animals using them. Humans have mimicked this shape in architecture after realizing how structurally sound it is.
This is why we see dome and arch shapes in buildings like bridges and churches. When a car is crossing a bridge, the arch beneath spreads the weight of the car, if it did not the weight would all be on one spot and could cause the bridge to collapse!
To really put this to the test, let's try another experiment! For this you will need two boxes of eggs. Cut the little carboard dividers that are between the eggs so that they are lower than the eggs when they sit in the box. Place the two boxes on the floor, make sure all the eggs are upright and even.
Sit on a chair and place your two feet on the eggs in the boxes (make sure you are wearing flat shoes for this part). Next, slowly stand up. You will find that the eggs can hold your weight without breaking! If you want to go even further try standing on one leg.