======Make a Thermometer======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Homemade Liquid Thermometer
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====Summary====                   
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====Procedure====  
  - Use a permanent marker to mark a clear plastic drinking straw with one centimeter intervals from the bottom up.  
  - Soften a small amount of modeling clay and flatten it into a round disk larger than the neck of a small bottle.  
  - Poke a hole through the clay using the straw to make a snug fit for the straw.  
  - Fill the bottle one-third to halfway with rubbing alcohol or water. Add a few drops of food coloring and shake gently to mix.  
  - Insert the straw through the hole in the clay and place the clay over the bottle’s mouth, ensuring the straw dips into the liquid but does not touch the bottom.  
  - Seal the neck of the bottle airtight using the clay, but keep the straw’s top open.  
  - Use a dropper to add more alcohol or water into the straw until the colored liquid level is visible in the straw.  
  - Mark the current liquid level as room temperature.  
  - Place the bottle in a bowl of ice water and mark the new level when the liquid stops moving (this corresponds to 0°C/32°F).  
  - Warm the bottle with your hands or place it in warm water to see the liquid rise, marking this higher level.  
  - Use your homemade thermometer to compare temperatures in different locations around your home.



====Links==== 
DIY: Build your own thermometer - WDIO: 
{{youtube>jKGtFnU50ek?}}\\

Make a Thermometer - STEM Activity - Science Buddies: 
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📄 Measure Up with a Homemade Thermometer - Science Buddies: [[https://www.sciencebuddies.org/stem-activities/homemade-thermometer]]\\

====Variations====
  * Build thermometers with straws of different diameters to compare accuracy.  
  * Calibrate your thermometer using a store-bought one to add a temperature scale.  
  * Use different colored liquids to make multiple thermometers for indoor and outdoor comparison.



====Safety Precautions====
  * Work in a well-ventilated area when using rubbing alcohol.  
  * Keep rubbing alcohol away from open flames - it is flammable.  
  * Avoid ingesting or inhaling alcohol fumes.  
  * Clean up spills immediately and wash hands after handling.  
  * Dispose of used rubbing alcohol safely by flushing it down the sink with plenty of water.




====Questions to Consider====
  * Why does the liquid rise when the thermometer is warmed? (The liquid expands as it heats up.)  
  * Why is it important to create an airtight seal around the straw? (It prevents air from escaping or entering, allowing accurate liquid movement.)  
  * What happens when the bottle is cooled? (The liquid contracts and moves down the straw.)  
  * Why is rubbing alcohol used instead of water? (It expands more uniformly and remains liquid over a wider temperature range.)  
  * How could you calibrate your homemade thermometer to measure actual temperatures? (By comparing the liquid levels to known reference points like ice water and warm water or using a commercial thermometer.)