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Also check out our Dinosaurs, Ice Age Mammals, and other Prehistoric Animals!

Take a look at this list of STEM themed movies and TV Shows to stay educated and entertained at the same time!

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The Earth's Layers

Earth split in half to show crust, mantle and inner and outer core

The Earth formed 4.54 billion years ago, starting out as an accumulation of meteorites, and has been bombarded by meteorites since. It is made up of three layers. They are:

1. Core

  • The core is in the very middle of the Earth
  • It is solid in the centre, and liquid on the outside
  • It is very hot!

2. Mantle

  • The largest part of the Earth
  • Molten, this is where lava comes from
  • 84% of the Earth's volume is mantle

3. Crust

  • The outer-most part of the Earth
  • Broken into many pieces
  • The smallest section
  • Where everything lives
  • Where we get the rocks and minerals that we use daily
You might be surprised to learn that the Earth is not solid! This fact allows for fascinating geological processes like Plate Tectonics and events like volcanoes, earthquakes, tsunamis, and the generation of new rocks.  

If you watch a pot of hot water boil you might notice that the hottest water at the bottom of the pot rises to the surface, while the surface water moves down. This same principle applies to the liquid section of our planet and is called a convection current. It is this process that moves the pieces of the crust. The incredible force built up over time as these plates move and collide can cause earthquakes and subsequently tsunamis, regions of volcanoes, and even build new land! 

What is a mineral?

A mineral is made of the same substance all the way through. There are about 5000 known minerals on Earth and many are essential for improving the way we live our lives. Almost any piece of technology, including what you're viewing this on now, uses specific minerals to function! Some minerals, like tiny amounts of copper and iron, are even required for human life.  

What is a rock?

A rock is made up of two or more minerals. Our homes, schools, places of work and roads are all made of rocks, we have learned a lot about which rocks are best for certain buildings and activities given their unique properties! Have you ever broken a piece of chalk? Then you know while it may be ideal for drawing, it would not make a strong building. 

There are three types of rocks. The Rock Cycle can be used to explain how rocks change from one type to another.

Rock Characteristics

  • Made of more than one mineral
  • Can be organic eg. Coal

Shared Characteristics

  • Solid
  • Naturally occurring

Mineral Characteristics

  • Made of one substance
  • Must be inorganic
  • Repeating internal structure
Rock Cycle Diagram

The Rock Cycle can be used to explain how rocks change from one type to another. Image: Santa Fe College 

Igneous rock example

1. Igneous

  • €‹Forms from liquid rock (lava and magma) 
  • Think of freezing water - as it cools crystals form
  • Other rocks can be turned into igneous rocks if they are heated so much that they melt
  • E.g., Granite
Metamorphic rock example

2. Metamorphic

  • Forms when an existing rock is re-heated (without fully melting). Involves a lot of heat and pressure
  • Think of a tadpole turning into a frog. It becomes something else on the outside while staying the same on the inside
  • E.g., Gneiss
Sedimentary rock example

3. Sedimentary

  • Forms from pieces of pre-existing rocks that undergo weathering and erosion followed by cementation 
  • Weathering is the process of breaking down an existing rock, and erosion is the process of moving the pieces of rock from one place to another
  • E.g., Petrified Wood, Ripple Marked Sandstone, Glacial Striae

Our Solar System

The Sun

What do you see when you look up into the night sky? Do you ever see stars? Let’s start at the most important star in your life: the Sun.

That’s right; the Sun is a star too! It is very hot, and a lot bigger than Earth. All of the planets in our solar system travel around it! We believe that the Sun formed about 5 billion years ago. By mass it is 71% hydrogen and 27% helium. 

Why is the Sun important?

  • It provides the Earth with energy. If there was no Sun there would be no life on Earth
  • It keeps us warm
  • It defines the seasons
  • The light produced tells us and animals when to sleep

Learn about the Sun's surface with this video...

Remote video URL

Rocky Planets

The rocky planets, from left to right: Mercury, Venus, Earth, Mars


Mercury is the closest planet to the Sun. It is very small and it has no moons. The entire planet is only slightly bigger than our Moon. It is made out of rock and it has not changed much since it was first formed. If we look at the surface of the planet we see a lot of craters, formed from asteroids hitting the planet!

  • Diameter: 3032.4 miles / 4880 km
  • Distance from earth: 36 million miles (57.9 million km)
  • Orbit around the sun: 88 Earth days
  • One Rotation: 59 Earth days
  • Moons: 0
  • Rings: 0
  • Your Weight: if you weigh 100 pounds on Earth, you would weigh 38 pounds on Mercury


Venus is the next furthest from the Sun. It is very similar in size to Earth. Have you ever heard about the greenhouse effect? It is currently causing our planet to warm up more than usual. This happened on Venus too. Venus had a lot of carbon dioxide in its atmosphere (a lot more than we do) and all the heat from the Sun got trapped under a thick layer of clouds. Because the heat has nowhere to go, Venus gets hotter and stays hot!

  • Diameter: 7520 miles / 12,100 km
  • Distance from sun: 67.24 million miles / 108.2 million km
  • Orbit around the sun: 225 Earth days
  • One Rotation: 243 Earth days
  • Moons: 0
  • Rings: 0
  • Your Weight: if you weigh 100 pounds on Earth, you would weigh 91 pounds on Venus


Earth is next to Venus. Our planet is very unique because it is the only one known to be able to support life.

  • Diameter: 7926.2 miles / 12,756 km
  • Distance from sun: 92.9 million miles / 149.6 million km
  • Orbit around the sun: 365.2 Earth days
  • One Rotation: 1 Earth day
  • Moons: 1
  • Rings: 0
  • Your weight: Your weight on Earth is the same


Mars sits next to Earth. There is little water on Mars at this time, but we think that it used to have large lakes or even oceans on it! Mars has two tiny moons which orbit close to it.

  • Diameter: 4,194 miles / 6,794 km
  • Distance from sun: 141.71 million miles / 227.9 million km
  • Orbit around the sun: 687 Earth days
  • One Rotation: almost 1 Earth day
  • Moons: 2
  • Rings: 0
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 38 pounds on Mars

Gaseous Planets


The gaseous planets, from left to right: Jupiter, Saturn, Uranus, Neptune


Jupiter is the biggest planet. It is made up of 90% hydrogen, and 10% helium. Jupiter is well known for its “red spot” which can be seen from space. It is believed that this red spot is an ancient storm of swirling winds which has lasted now for hundreds of years. The red spot is big enough to hold two Earths!

  • Diameter: 88,736 miles / 142,800 km
  • Distance from sun: 483.88 million miles / 778.3 million km
  • Orbit around the sun: 12 Earth years
  • One Rotation: 9 hours, 55 minutes
  • Moons: 79
  • Rings: 4
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 265 pounds on Jupiter


Saturn is smaller than Jupiter, but still much larger than Earth. Saturn is well known for its rings, which are made up of small particles (rocks, ice, water and gases) circling the planet.

  • Diameter: 74,978 miles / 120,668 km
  • Distance from sun: 887.14 billion miles / 1,427 billion km
  • Orbit around the sun: 29 ½ Earth years
  • One Rotation: 10 hours, 40 minutes, 24 seconds
  • Moons: 53-82
  • Rings: 7
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 108 pounds on Saturn


Uranus appears blue because its upper atmosphere is made up of methane. The planet has coloured bands, but they are hidden. Uranus spins differently than the other planets, it spins sideways!

  • Diameter: 32,193 miles / 51,810 km
  • Distance from sun: 1,784 billion miles / 2,870 billion km
  • Orbit around the sun: 84 Earth years
  • One Rotation: 17 hours
  • Moons: 27
  • Rings: 11
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 86 pounds on Uranus


Neptune is also blue because of the methane gas in its atmosphere. It also has the fastest winds of any other planet (recorded winds of 2000 km/s)!

  • Diameter: 30,775 miles / 49,528 km
  • Distance from sun: 2,769.46 billion miles / 4,497 billion km
  • Orbit around the sun: 687 days
  • One Rotation: 16 hours and 7 minutes
  • Moons: 14
  • Rings: 4
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 114 pounds on Neptune

Dwarf Planet


Pluto is now a dwarf planet because of its size and location


Pluto has been our favourite dwarf planet since 2006. It appears to spin on its side, with its equator pointing up and down and the poles pointing to either side. Pluto is by far, smaller than any of the planets. It has five moons orbiting it. A NASA spacecraft took images of Pluto for the first time in 2015, 5 billion kilometres from Earth, and captured surprising features like young mountain ranges!

  • Diameter: 1,423 miles / 2,290 km
  • Distance from sun: 3.666 billion miles / 5,900 billion km
  • Orbit around the sun: 248 Earth years
  • One Rotation: 6 days, 9 hours, 18 minutes
  • Moons: 5
  • Rings: ?
  • Your weight: if you weigh 100 pounds on Earth, you would weigh 7 pounds on Pluto

Water Cycle

What happens to the rain after it hits the ground? Where does it go and where did it come from? Let’s start at the beginning!

Earth does not lose or gain any substantial amount of water. The water that we have, we got when the Earth was just being formed. This means that the water in your cup has been around for many hundreds of millions of years. It gets recycled through a process called the water cycle.

Water Cycle Diagram

1. Evaporation

Have you ever left a glass of water out on the table for a few days before? If so, did you notice all of the water slowly disappear? This is caused by evaporation. The liquid water is turning into water vapour!

The evaporated water floats up into the atmosphere and combines with small pieces of dust. When the water and the dust collect, they form clouds in the sky.

Transpiration: Lakes, rivers, and open cups of water aren’t the only places that the clouds get water from. Water also comes from plants! The plants take water out of the ground through their roots and then they “sweat” through their leaves! Transpiration is the special name for evaporation off of plants. 

2. Condensation

When the water is in the clouds it can’t stay in its gas form for too long. It is cold high up in the sky, so the water turns back into liquid or even ice. This process is called condensation.

3. Precipitation

Clouds can only hold so much water. When they get really full they release the water as precipitation.

Precipitation can be rain, snow, hail, sleet, or any other kind of water that falls from the sky. Most precipitation starts off as a solid and melts as it falls.

4. Ground Water and Runoff

But where does the water go when it hits the ground? That’s a harder question to answer.

When the rain hits cement, like when it lands on a road or a sidewalk, it may stay in one place and collect in a puddle. This is why we have storm drains on the side of the road for the water to go into. They give this pooling water a place to go so that our roads don’t get too flooded. These storm drains collect the water and then release it into streams, lakes, rivers, and oceans. We have to be very careful about what we put in these drains because the fish and other inhabitants of lakes, rivers, and oceans will be harmed if we put toxic things in them.

When the rain falls on grass, plants, or dirt it doesn’t usually form puddles. Why? We will call these places “green spaces”. Think of them as giant sponges, they soak up the water and slowly let it travel through the ground because soils have space in them for water to fill and flow through. In Waterloo, we actually get most of our drinking water from the ground! We have lots of wells that suck up water from under the ground.

Sometimes when it rains a lot, the ground cannot soak up all the water in time and it runs off the land and into streams, oceans, and lakes. This is called runoff.

When it snows the same thing happens, but there is a delay while the water stays in one spot until it melts and then continues through the water cycle.

5. Accumulation

Water sometimes collects and stays in one place for a really long time. This is called accumulation. Water in oceans and lakes sometimes spends thousands of years in one place until it is evaporated again.

Ecosystem Interactions and Change

Ecosystem Interactions

Ecosystems are composed of living (biotic) and non-living (abiotic) parts that interact and rely upon each other. The size of an ecosystem can depend on the scope of the person observing it, interactions occur at small scale levels, like the ecosystem in your gut, or large scale like the Great Lakes region.

It’s important to remember that ecosystems are not designed! They function well because natural selection favours creatures that can exploit their environment, for instance, using abundant available resources.

Energy is not created or destroyed. This is one of the basic principles of physics, but it applies to all sciences. Life requires energy (food/fuel) is a fundamental biology concept. In an ecosystem energy is transferred up and around by different types of interactions.  

Type of Interaction Example, Description, (Positive or Negative)
Predation Wolves and Dear. Wolves are the preditor and dear are the prey. Typically, these are lethal relationships.  ( +, - )
Parasitism Humans and Leaches. Leaches benefit from our blood loss. Typically, these are not lethal relationships. (+, - ) 

Bees and Flowers. Bees get nectar and flowers spread their pollen. ( +, + )


Different bird species compete for limited ideal shelter, this isn’t good for either party. ( - , - )

Commensalism Lichens and Trees. The tree is unaffected while the lichens that grow on it get access to more sunlight. ( +, neutral)


  • The creature that eats another or damages another for its own benefit
  • Eg. Wolves


  • The creature that is eaten or damaged for the predator's benefit
  • Eg. Dear

Primary Producer

  • A creature that harnesses the energy from a non living source, usually the sun
  • Eg. Clovers

Image: National Geographic - Tim Gunther 

Trophic Levels

Primary producers are energy gateways! Plants and other organisms that photosynthesize (capture the suns energy) bring energy into an ecosystem in a usable form for other species. From there those that eat the plants gain some of their energy.

When an animal eats another animal (or a plant) only about 10% of the prey’s energy is retained by the predator, the rest is left behind or was used up and released during the prey’s life. So, if a dear only gets 10% of a plant's energy they have to eat many more plants. This theory explains why predators are much fewer in number than primary producers. It also explains why populations don’t grow out of control, more wolves can’t survive long-term if their prey populations remain the same.

Human intervention into these natural balances creates issues. Areas of Southern Ontario have seen a growth in dear population as wolf numbers drop (human activity scares them and has destroyed their habitats). Having so many dear has made roads more dangerous and damaged more crops.

Energy flow doesn’t stop when we get to the top predator in an ecosystem! Even that animal will pass, and their energy will be returned to lower levels and they will feed the microorganisms in the soil and scavengers.

Ecosystem interactions are not just related to life and death though. The shade of trees cools the forest below, beaver dams shape aquatic environments, and snow can insulate the ground.

Try removing or doubling the population of your favourite species, can you predict a chain of 5 changes? Or even 10?

Past Ecosystems

Over the course of the 3.7 billion years life has existed on our planet it has continued to change! Humans have only been around for 200-300 thousand years and we have drastically changed the planet we live on. We have brought foreign creatures to distant lands (invasive species), created new species through breeding (woof woof), and dramatically increased the populations of our favourite animals like cats and dogs!  

But what about before us? It is estimated that over 99% of all species that have ever existed have gone extinct, that’s around 5,000,000,000 species. You may be familiar with some of the more infamous ones like Dinosaurs and the Megalodon that you see in movies, but these creatures didn’t live alone. They had thriving complex ecosystems like ours!

Western Interior Seaway

If you’re familiar with plate tectonics you know that land masses or continents are changing and moving. Significant portions of Canada were much closer to the equator in the past and if you think about the tropics today, you know that they have very different plants and animals. What is above water today probably wasn’t always, shallow seas covered areas of Canada for millions of years and they evolved their own odd life forms. While we can’t see these ancient ecosystems in action, we do have access to the fossils some left behind, and we possess the tools to date them!  

Image: Earth.com

Sea Scorpion

You can have a lot of fun googling extinct creatures, try words like, largest, scariest, and strangest extinct animals and plants!  Pictured here is an artist's rendering of a Sea Scorpion based on fossil evidence. 

Image: Yale University - Patrick Lynch

Future Ecosystems

It is important to remember that ecosystems have always changed, and things go extinct naturally! Though you might have heard terms like Climate Change, Global Change and Global Warming, so what are they talking about? While ecosystems change, and extinction happens, both usually happen at very slow rates, sometimes called background extinction. The problem is scientists know that these things are happening much more quickly in the last 200 years. Through extensive research we know that human activity has changed the composition of our atmosphere to include more gasses that trap more heat, in particular carbon dioxide, CO2. We also know that our expanding presence has taken up more land, and we’ve pushed animals and plants out of large spaces further increasing the rate of extinction while decreasing biodiversity.  

Diagram of the green house effect

The Green House Effect describes how some incoming radiation escapes and other remains. Without this effect Earth would be freezing! The issue is we are increasing the amount of retained energy by changing the atmosphere's composition. Image: The Open University

Human created climate change has lots of implications, we simply can’t list them all and we likely don’t know of them all yet. Major ones include rising sea levels and more extreme weather like floods, droughts, and heat waves. These problems have implications outside of the obvious, many people will be displaced, and tropical diseases may extend their ranges.  Human created climate change is already in motion and we have a limited amount of time to take drastic action. Countries have begun making changes to ensure we avoid the worst effects, but we need further action and cooperation to tackle this crisis and protect our ecosystems.

It’s not all doom and gloom though! Action like the Paris Agreement show international cooperation and recognition of climate change is increasing. 2020 saw thousands of people take to the streets to voice their desire for serious action to combat climate change.