![Air conditioner and plant](/sites/default/files/styles/resource_card_image_360x300_/public/2024-06/2024_Stock_AirConditionerPlant_Bil_ResourceHeader.jpg?itok=KAF0Wpna)
Humidity: Outdoors and Indoors
Backgrounders
Learn about the importance of humidity, its sources and how people control it indoors.
![Katie Mack headshot](/sites/default/files/styles/career_image/public/2023-01/Katie%20Mack.jpg?itok=OZ3DZ4TV)
Katie Mack (she/her)
Career Profiles
Hawking Chair in Cosmology and Science Communication
![physical and chemical changes header](/sites/default/files/styles/resource_card_image_360x300_/public/2022-11/physical%20and%20chemical%20changes%20header.jpg?itok=dmgnc95b)
Exploring Physical and Chemical Changes
Lessons
Students observe and classify physical and chemical changes of matter.
![Sea ice](/sites/default/files/styles/resource_card_image_360x300_/public/2021-12/sea_ice.jpg?itok=Smv2NiTH)
Ice on Earth - The Cryosphere
Backgrounders
Learn about the cryosphere and how it is being impacted by climate change.
![Hand writing chemical equations](/sites/default/files/styles/resource_card_image_360x300_/public/2021-10/writing_chemical_equations.jpg?itok=aOerl6xI)
Chemical Equations
Backgrounders
Learn about how to write and balance chemical equations.
![Heating a liquid over a flame in a lab](/sites/default/files/styles/resource_card_image_360x300_/public/2021-11/reaction_types_header.jpg?itok=RwhxbpFu)
Types of Chemical Reactions
Backgrounders
Learn about the four main types of chemical reactions.
![Periodic Table with molecular model](/sites/default/files/styles/resource_card_image_360x300_/public/2021-11/benzene_periodic_table.jpg?itok=fCC8x3H6)
Introduction to the Periodic Table of the Elements
Backgrounders
Learn about the elements of the periodic table and how they are organized.
![Cloud model of an atom](/sites/default/files/styles/resource_card_image_360x300_/public/2021-01/cloud_model_atom.jpg?itok=3YgrftL8)
Introduction to the Atom
Backgrounders
Learn about the parts of an atom and its history.
![Cube overflowing with spheres representing particles](/sites/default/files/styles/resource_card_image_360x300_/public/2020-12/cube_filled_with_particles.jpg?itok=bKfAvtCi)
Introduction to the Particle Theory of Matter
Backgrounders
Learn about how the Particle Theory helps us understand matter.
![Snowflake](/sites/default/files/styles/resource_card_image_360x300_/public/2020-10/snowflake.jpg?itok=DpMn15sa)
Weather: Precipitation
Backgrounders
Learn about humidity and the many forms of precipitation.
![Ice technician on a zamboni at an outdoor skating rink](/sites/default/files/styles/resource_card_image_360x300_/public/2020-06/zamboni_outdoor_rink.jpg?itok=nSmM8N5Y)
The Hidden Heroes of Hockey!
STEM Explained
Ice Technicians use math and physics in order to keep the ice ready for hockey.
![Casting hot iron](/sites/default/files/styles/resource_card_image_360x300_/public/2020-04/casting_hot_iron.jpg?itok=mE6eP_bv)
What Causes Hot Things to Glow?
STEM Explained
Getting electrons excited by heat can cause certain materials to give off visible light when heated - like filaments in light bulbs.
![Solid, liquid and gas](/sites/default/files/styles/resource_card_image_360x300_/public/2020-01/solid_liquid_gas_header.png?itok=7jS9ACAN)
States of Matter
Backgrounders
Learn about the states of matter, as well more about one state in particular - gas!
![People playing ice hockey](/sites/default/files/styles/resource_card_image_360x300_/public/2020-06/people_playing_hockey.png?itok=pPcyU2JG)
Why Do Ice Rinks Stay Frozen?
STEM Explained
Every ice rink is an example of molecular bonding and gas laws at work!
![Why is rain not salty?](/sites/default/files/2019-08/why-is-rain-not-salty.jpg)
Why is rain not salty?
Hands-on Activities
Make a model of the water cycle and find out how water moves around on planet Earth.