Food In The Classroom: Science Experiments Using Lemons And Eggs

Reference & Education

  • Author Harvey Mcewan
  • Published March 1, 2013
  • Word count 661

For many children around the world, learning about science can be a dull and often complicated experience. However, it doesn’t have to be this way. There are plenty of ways for teachers and parents to make science fun and memorable using simple household items.

Using commonly available items like eggs and lemons, for instance, it’s easy to demonstrate simple scientific concepts such as how forces and electricity work.

Fun experiments with eggs

An easy demonstration to begin with for young science students is how to squeeze an egg without breaking it. Make sure each student has their own raw egg and instruct them to place it in the palm of their hand. Each hand should then close around the whole egg, applying pressure evenly all around it. Children who have never done this experiment before will most likely expect it to break. So if anyone is feeling nervous or scared about making a mess with their egg, give them a small plastic bag in which to conduct the experiment for reassurance. If the experiment is done properly, the egg will not break. That’s because the egg’s curved surface means that pressure distributed evenly does not cause it to crack, explaining why a hen can sit on an egg without breaking it. However, applying uneven pressure – for instance, cracking part of an egg along the side of a bowl – means that it breaks easily.

Another great classroom experiment with eggs helps to explain density to young students. For this experiment, you will also need salt, water and a glass that’s wide enough to comfortable fit an egg. Dissolve around three tablespoons of salt in 250ml of water to make a very salty solution. Fill a glass halfway with this salty solution then carefully top it up with plain water. The two kinds of water shouldn’t mix, so tip the glass at an angle and pour the plain water along the side of the glass so it sits on top of the salt water. Then, carefully place the egg into the glass. You will see that the egg will sink through the plain water but when it meets the salty water, it will stop moving so it floats in the middle of the glass. That’s because salt water has a much higher density than plain water, so it’s a great way to explain to children why people float so easily on the Dead Sea.

The learning potential of lemons

Lemons are also a great way to teach children about elementary scientific concepts. Start by making invisible ink with lemon juice. Squeeze a lemon into a bowl and add a couple of drops of water. Then dip a cotton bud into the juice and water mixture and use the wet end to write something small on a piece of paper – for example, get a child to write their name. The writing will be barely noticeable. When the paper is dry, hold it close to something warm like a light bulb. As it heats up, the letters will begin to show up, making the invisible lemon ink visible. This happens because when lemon juice is heated up, it oxidises and turns brown. This experiment can also be done with orange juice or vinegar.

Another effective classroom experiment with lemons is making a fruit battery. This experiment is a little more technical so may be more suitable for older children and may need to be conducted in a lab. There are many different ways to do this experiment but you will always need a lemon, two different types of metal (like a copper coin and steel pin or a zinc-coated nail), and some wires with alligator clips to hook up to a device that will measure electric current. By inserting both types of metal into the lemon and connecting it with alligator clips to a multimeter, you can measure how many volts of electricity the lemon battery emits.

Harvey McEwan provides fund and exciting science experiments for children, including a fruit battery and many more. View Harvey's other articles to find out more.

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