How to Make a Homemade Thermometer?

It can be said that the thermometer is one of the most widely used instruments in the world, due to its ability to measure the temperature of the environment, a substance, material, or specific object, the thermometer has various uses from the domestic, the clinical to the scientific. Teaching children about this wonderful invention of Galileo Galilei is something that will surely seem incredible to them and that will strengthen ties between parents and children. Making a thermometer at home is easy and can be very fun for children, it is a playful activity that leaves them learning.

Although home thermometers are not able to record exact measurements, it allows you to experience the changes in temperature and how it affects the liquid it contains and thus as the temperature around the home thermometer increases, the liquid inside expands and rises, such what is the operation of the thermometers of industrial manufacture since it follows the same principle of dilation and likewise when the temperature goes down, the liquid will contract to its original shape and position.

The interesting thing about this experiment is that in addition to making a useful object that will allow us to measure the temperature, it will allow us to see and feel in real-time how the liquid changes as the temperature rise or falls.

There are different scales to measure; in this case, the measure will be through observation, the important thing is that children begin to understand the functioning of this common as well as the interesting object.

Materials to make a homemade thermometer

To make a thermometer at home is not necessary to make a large economic investment or try to get difficult elements, this experiment can be done with things that we live with daily, everyday things that we have at home, the materials to use are the following:

• 1 Disposable container with capacity for one liter
• 1 Transparent plastic bottle with lid, with a capacity of approximately half a liter (16-20 ounces). (Remember that you can reuse a bottle of soda or water, as they are more resistant.)
• Tap water
• Alcohol (approximately 300 ml or the amount needed to fill half a bottle)
• One transparent straw at least 20 cm long (In some countries it is known as a straw, straw, straw, straw or cigarette).
• One piece of plasticine
• 1 Hot nail or metal object with which the bottle cap can be punctured.
• 1 Plastic Funnel. (to fill the bottle once the mixture is prepared)
• Liquid artificial coloring. (You can use edible vegetable dye).
• 3 Markers or permanent ink markers of different colors.
• A bowl or glass (200 ml) with cold water
• Various ice cubes
• A bowl or glass (200 ml) with hot water

Once you have gathered all the materials needed to make this homemade thermometer, remember to cover the surface where you are going to make it avoid that if spills of liquids or ink, it can be damaged or stained.

Procedure for making a home thermometer

1. In a bowl pour enough alcohol to fill the bottle halfway.
2. Add in the container with alcohol one or two drops of artificial dye, it is advisable to use the color red to simulate the mercury contained in the real thermometers, stir until the alcohol is painted with the dye.
3. Pour the colored alcohol into the bottle, you can help with a funnel to avoid spilling the alcohol out of the bottle.
4. Pierce the lid of the bottle and insert the straw into the hole.
5. Then close the lid and seal it with the plasticine so that no open hole is left and the straw stays fixed in place. It is important that the straw does not touch the bottom of the bottle.
6. On one side of the bottle, mark the level of alcohol inside the bottle when it is at room temperature.

How to check the operation of the home thermometer?

To check the thermometer at low temperatures

You can place the bottle in the container with water and ice cubes; you can also place it inside the refrigerator, freezer, or somewhere where you receive a direct source of cold; by doing so for a period you will see that when the temperature drops, the liquid contracts and occupies less space.

When this happens, mark in a different color than the one you used to make the original mark when the liquid was at room temperature, to keep track of the variation of the liquid level between the start and the current moment of the experiment.

To check the thermometer at high temperatures

Place the bottle near a hot zone or a source of heat, such as an oven, a stove, the sun’s rays, or simply hold the bottle and watch as your body transfers the heat from your body; You can also try to raise the temperature of the liquid with the warm air of a hairdryer (remember to do this with help and authorization from an adult).

As the temperature around the bottle increases, the liquid inside will expand and begin to move up, indicating an increase in temperature.

When you begin to observe these changes, mark in a different color from the original and the one you used to check the thermometer in the cold and at room temperature, to keep track of the variation of the liquid level in a warmer environment.

Tips to consider

• Remember that when handling alcohol, you should try not to spill it or fall on mucous membranes.
• When you go to open the hole to the top, you should avoid cutting or hurting yourself with the object you use, if you are a child ask for help from an adult.
• When you are going to perform the experiments of cold and heat, try to use gloves or a cloth not to burn yourself with the hot water.