![Boat on a lake at sunset](/sites/default/files/styles/resource_card_image_360x300_/public/2021-01/boat-docked-on-lake-at-sunset.jpg?itok=1QlQiekK)
Humans and Freshwater Ecosystems
Backgrounders
Learn about how people impact the ecosystems of lakes and rivers.
![Some examples of biomass](/sites/default/files/styles/resource_card_image_360x300_/public/2021-01/biomass_icon.png?itok=6lz_OKwA)
Generating Electricity: Biomass
Backgrounders
Learn how biomass can be used to generate electricity.
![Ian Cook](/sites/default/files/styles/career_image/public/2021-01/Ian%20Cook.jpg?itok=L8Z4nvIF)
Ian Cook
Journeyman Sheet Metal Worker
![Coal and natural gas fueled generator near Hanna, Alberta, Canada](/sites/default/files/styles/resource_card_image_360x300_/public/2020-12/coal_power-generating-station.jpg?itok=cFUVGxpm)
Generating Electricity: Fossil Fuels
Backgrounders
Learn how energy from fossil fuels can be used to generate electricity.
![Skyglow from a city and highway](/sites/default/files/styles/resource_card_image_360x300_/public/2020-06/night_sky_and_highway.jpg?itok=5QVvQWHE)
Light Pollution
STEM Explained
Light can be a type of pollution. Learn about the damage it causes to people and living things as well as how you can prevent it.
![Photo de Sheila Sadler au travail](/sites/default/files/styles/career_image/public/2020-02/Sheila%20Sadler.jpg?itok=kQFTQRgb)
Sheila Sadler
Sheet Metal Journeyperson
![Platinum crystals](/sites/default/files/styles/resource_card_image_360x300_/public/2020-02/Platinum-crystals.jpg?itok=CIVtGM1E)
Catalytic Converters
STEM Explained
Learn about how catalytic converters make vehicle emissions less harmful.
![Cartoon leaf holding an umbrella over baby plant](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/cartoon_acid_rain.jpg?itok=J4BMIwgR)
What is Acid Rain?
STEM Explained
Acid rain is any precipitation that has an unusually low pH. It can be rain, snow, fog, etc. But what is a low pH and why is this a problem?
![Hamilton Street Railway bus in downtown Hamilton, Ontario © Adam E. Moreira [CC BY-SA 3.0], Wikimedia Commons](/sites/default/files/styles/resource_card_image_360x300_/public/2019-08/Hamilton%20Street%20Railway%20bus%20in%20downtown%20Hamilton%2C%20Ontario%20%C2%A9%20Adam%20E.%20Moreira.jpg?itok=1ZSDJMZQ)
Fueling Internal Combustion Engines
Backgrounders
Learn about the wide variety of fuels used in vehicles.
![Hamilton, Ontario industrial area with Toronto skyline in the background](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/the-hamilton-industrial-area-with-toronto-skyline.jpg?itok=shKtb5Tb)
What are Greenhouse Gases?
Backgrounders
This backgrounder explains what greenhouse gases are and how they contribute to climate change.
![What are the best materials to use for cleaning water?](/sites/default/files/2019-08/what-are-the-best-materials-to-use-for-cleaning-water.jpg)
What are the best materials to use for cleaning water?
Hands-on Activities
Water is a precious natural resource. What happens if it gets polluted? Learn how water can be cleaned with this hands-on activity?
![What are the effects of acid rain on rocks?](/sites/default/files/2019-08/what-are-the-effects-of-acid-rain-on-rocks.jpg)
What are the effects of acid rain on rocks?
Hands-on Activities
Learn about the chemical reaction that happens between acid rain and limestone.
![Nitrogen symbol from periodic table](/sites/default/files/styles/resource_card_image_360x300_/public/2021-03/the-periodic-table-element-nitrogen.jpg?itok=bs_Xbeg4)
Understanding the Nitrogen Cycle
STEM Explained
What is the nitrogen cycle? How do human activities such as using fertilizer affect the nitrogen cycle? How can this cause greenhouse gases?
![Students looking bored in class](/sites/default/files/styles/resource_card_image_360x300_/public/2019-09/Students_looking_bored_in_class.jpg?itok=Wr5c_zOj)
Is There Too Much Carbon Dioxide in Your Classroom?
STEM Explained
Did you know that too much carbon dioxide in the classroom can affect your body, and even your grades?
![illustration of a hydrogen car](/sites/default/files/styles/resource_card_image_360x300_/public/2019-10/Hydrogen_car.png?itok=-Ul7H9-e)
The History and Uses of Hydrogen
STEM Explained
Hydrogen’s tendency towards combustion is what makes it both a dangerous chemical element and a useful energy source.