Project Hot Hot Hot

This lesson resource was created by Downside School in the UK.

Topic:  Humidity

Learning Objectives

  • Define humidity as the amount of water present in the air (measured in %)
  • Take readings of humidity in two different locations
  • Identify and describe humidity changes on a graph and link to a daily cycle

Think further about the relevance of tracking environmental factors over extended periods of time. 

Students:  Age 12, low maths ability, pupils with additional learning needs (Dyslexia, dyscalculia, focus and concentration)

Time:  60 minutes

Prior learning:  Lesson 4 of 8 in a sequence on heat and temperature probes.  Students have used thermometers and probes to investigate temperature change during the course of chemical reactions.  Students have not yet been introduced to the exploratory.

School:  Downside School

Starter. We are going on a school trip to the rainforest.  What things might you pack if you were going out of school for the day? Get students to write down answers or respond verbally. Elicit idea that they would pack a drink and food. Elicit idea that different clothing may be necessary due to different temperature and humidity. 

Task 1 – What is humidity? Share with students that a type of animal lives in the rainforest that never ever drinks, as it is able to get all of the water it needs from the air.  Share with students a definition of humidity as the amount of water that is present in the air.  Get a student to read the humidity of the classroom from the IoT device.  Explain that humidity is measured in %.  This information can be reinforced with powerpoint slides that are also provided for the students. 

Task 2 – Visit to the dart frogs Share with the students that the type of animal is a dart frog and take students to visit the dart frog terrarium.  Ask students to take a reading of the humidity.  Is this higher or lower than the classroom?  Why is it less than 100%?  What would it feel like to be in a room with a humidity this high?  Has anyone ever been to a very hot swimming pool / spa?  What do students think will happen to the humidity if the teacher opens the terrarium and sprays some more water in?  Do so, and observe any increase on the IoT device display.

Task 3 – What is the point in tracking environmental conditions?  Explain to students that we have just taken two humidity readings, which are like a snapshot in time, but that these devices can also be used to track humidity over time.  Ask students why we might want to do this?  What could be the benefits of tracking the conditions in a terrarium?  Show students exploratory readings for terrarium vs classroom today. Look for the moment when the teacher sprayed the additional water in!

Click here to build the data in the Exploratory tool. Scroll to the humidity graph.

Task 4 – When is danger time for the frogs? Work through the worksheet with 5 days of terrarium vs. classroom data.  To support those with low mathematical confidence, students could be guided to colour code the legends and add a “danger” line at 70% (i.e. if the terrarium falls below this, it could be dangerous).  Support students to annotate the peaks J and troughs L

Task 5 – Evaporation and humidity Explain to students that at humidity’s below 70% the frogs are in danger of becoming dehydrated.  This is because water can evaporate from their skin at lower humidity’s.  Explain to students that evaporation is the process by which water on the skin (e.g. sweat) turns into water vapour.  This evaporation also has a cooling effect which is why humans sweat when they need to cool down.  Share with students the main sources of water gain (drinking, eating, metabolism) and water loss (urination, sweating) in humans.  How are humans different to frogs?

Task 6 – Wet and dry bulb thermometers Explain to students that evaporation and the associated cooling effect can be used to calculate the humidity.  Demonstrate this to students and help them calculate the humidity of the classroom using a conversion table.  More able students could do this on their own. 

Plenary – Use extended Q&A to recap learning principles and lead reflection on outcome of wet/dry bulb thermometers.  Compare this calculated value to the reading the IoT probe is giving.  Why might they be different?