How to Make Your Own Thermometer

Lena and Petya always looked forward to the moment when they could do a new science experiment in the kitchen. They had already tried many different experiments, but today they decided to make something special – a thermometer with water, dye, and a straw.

— Did you know we can make our own thermometer? — Lena started, holding a plastic straw. — We’ll use water, dye, and a straw to measure temperature. This will be a simple and very interesting project!

Petya looked at his sister curiously:

— Really? I always thought thermometers had to be complicated. Do you think we can make a real thermometer?

— Of course, — Lena answered confidently. — We’ll use the principle of liquid expansion when heated. When water is heated, its molecules begin to move faster and it expands, which will allow us to observe this process through the straw.

The two started gathering materials for the experiment. Lena brought a plastic straw, a clear bottle, some water, dye for the water, and modeling clay for sealing. All the necessary tools were at hand, and now they could begin their experiment.

— We need to pour some water into the bottle, — Lena said as she poured water into the clear bottle. — This will be the base for our thermometer.

Petya happily helped his sister fill the bottle halfway. When the water was ready, Lena added a few drops of dye to make the liquid bright and clearly visible through the straw.

— Now we can see the water in a bright color, — Lena said. — And we will be able to observe how it expands or contracts in the straw when the temperature changes.

After the water was colored, Lena inserted the straw into the bottle's neck. For sealing, they used modeling clay to ensure no water leaked out or evaporated. Petya carefully sealed the straw with the clay, leaving a small gap for the water to move up the straw.

— Perfect! Now we have a simple model of a thermometer, — Lena said. — Let’s see how it works!

They began experimenting with the water temperature. First, they placed the bottle with the thermometer in cold water and carefully observed how the water level in the straw did not change. Then, to compare, they decided to heat the water in a pot to see how the water expanded when heated.

— Look, the water is starting to rise up the straw! — Petya exclaimed as he saw the water level rise in the straw. — That’s because the water expands when its temperature increases!

Lena nodded:

— Exactly. This is what we see in real thermometers. When the temperature rises, the liquid expands, and we can measure its temperature by observing the liquid level. This is how mercury and alcohol thermometers work.

The two continued experimenting with different temperatures, placing the bottle in hot water and in ice-cold water. Each time the temperature changed, they saw how the water level in the straw changed.

— This is amazing! Now we know how thermometers work, — Petya said. — And we made our own model that helps measure temperature!

— Yes, and this is just the beginning, — Lena replied. — We can use this thermometer to study not just the temperature of water, but other substances as well. For example, we can try measuring the air temperature or even check the temperature in different parts of the room.

The two looked proudly at their homemade thermometer and decided to conduct additional experiments to explore how different materials react to temperature changes. Lena suggested doing experiments with different liquids to understand how other liquids expand or contract when heated and cooled.

— Let’s check how salt or sugar in water affects the temperature and how the liquid will expand in the straw, — Lena suggested. — This will be our next experiment!

Petya was excited by the idea, and they decided to continue their experiments to explore how temperature affects different substances. This was their first step into the world of physics and chemistry, and they were happy to have learned how to create their own temperature-measuring tools, and in such a fun way.