All Lesson Plans

Make a Hygrometer to Measure Humidity

Grade Range
3rd
Group Size
2-3 students
Active Time
2 hours 15 minutes
Total Time
2 hours 45 minutes
Area of Science
Weather & Atmosphere
Key Concepts
Humidity, hygrometer, weather
Learning Objectives
  • Explain what humidity and evaporation of water are
  • Understand and give examples of processes that increase and decrease humidity
  • Record qualitative humidity data taken with a hygrometer

Overview

What do a crazy hair day, a wooden door stuck in its frame, and the weather have in common? Humidity! In this fun hands-on weather lesson students explore surprising information about human hair, the air around them, and the weather by building a hygrometer from a strand of hair, a straw, a wooden panel, and two nails. A great way to make humidity visible!

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
  • 3-ESS2-1. Represent data in tables and graphical displays to describe typical weather conditions expected during a particular season.
  • 3-ESS2-2. Obtain and combine information to describe climates in different regions of the world.
This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Constructing Explanations and Designing Solutions. Use evidence (e.g., measurements, observations, patterns) to construct or support an explanation or design a solution to a problem.
ESS2.D: Weather and Climate. Scientists record patterns of the weather across different times and areas so that they can make predictions about what kind of weather might happen next.
Cause and Effect. Cause and effect relationships are routinely identified, tested, and used to explain change. Events that occur together with regularity might or might not be a cause and effect relationship.

Credits

Sabine De Brabandere, PhD, Science Buddies

Materials


Materials needed to make a hygrometer as described in this STEM lesson plan.

Per group of 2 to 3 students:

  • 1 tsp rubbing alcohol (70% isopropyl alcohol works well)
  • Measuring spoons
  • Small bowl
  • Water
  • Two long strands of human hair (about 20 centimeters each), one to use and another as backup (strands from straight, wavy or curly hair are fine, frizzy hair makes it a little more difficult).
  • Cotton swab
  • Drinking straw (preferably a wide, non-bending straw)
  • Scissors
  • Metric ruler
  • Glue (fast drying glue or a glue gun work best)
  • Scrap piece of wood (about 25 cm long and 15 cm wide)
  • Two short nails (must be longer than the diameter of the straw)
  • Marker, pencil, or pen

One for every other group:

  • Resealable bag (large enough to fit the wood inside and have a little room to spare)
  • Wet sponge or small towel (either paper or cloth)

To be shared among several groups:

  • Hammer
  • Hair dryer
  • Optional: windows that face a colder area (e.g. outside on a not too hot day), or drinking glass cooled by ice-cubes.
  • Optional: waterproof paint, paint brushes and other materials to decorate their hygrometer.

For the class:

  • Plate
  • 1/4 cup measuring cup

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Grade Range
3rd
Group Size
2-3 students
Active Time
2 hours 15 minutes
Total Time
2 hours 45 minutes
Area of Science
Weather & Atmosphere
Key Concepts
Humidity, hygrometer, weather
Learning Objectives
  • Explain what humidity and evaporation of water are
  • Understand and give examples of processes that increase and decrease humidity
  • Record qualitative humidity data taken with a hygrometer