The Big Bang Lesson Plan
Lesson objective: Students will be able to explain our place in the universe by using the terms solar system, galaxy and universe. They will also be able to explain the Big Bang theory of how the universe began.
Materials: pictures of the solar system, galaxies, and the universe; a frisbee; YouTube video
Length: 1 class period (50 minutes)
Do you know where you are?
Ask the students where they are right now. Get them to be as specific as possible, starting from their desk and then working their way through: the classroom, the school, the neighbourhood, the city or town, the province or state, the country, the continent, etc. all the way to "We are on the planet Earth". Then ask: "But where is Earth?" Answer: the solar system.
The solar system is a group of planets going around a sun (show slide). Our sun is actually a star. It looks bigger than other stars simply because it is much closer to us. In actual fact, many stars are far bigger than our sun.
Have you ever wondered whether other stars also have planets going around them? Well, up until 2003, humans did not actually know the answer to this question. However, in that year, the first planet outside of our own solar system was discovered. Since then scientists have discovered many other "solar systems" and have found over 400 planets going around other stars.
So now we know that we are in the solar system. But where is our solar system and all the other stars and planets located? Answer: inside a galaxy.
A galaxy is a large group of stars grouped together, usually in some sort of pattern. Each galaxy is made up of billions of stars (one billion = 1,000,000,000)! There are many different types of galaxies (show slides). Ours is called the Milky Way and looks like a spiral.
Of course, we can't actually see a picture of our own galaxy. Why? Because we are inside it! However, on a very dark night you can see a cloudy path (which is actually not a cloud) stretching across the entire the sky (show slide). The milky color of this path is where our galaxy gets its name.
To understand what you're seeing, think of a galaxy as being like a giant roti. Since we are inside the roti and the roti is flat, all we can see when we look up is a ring around the sky (Use the frisbee to demonstrate this).
So, once again, we now know where we are. We are inside the Milky Way galaxy. But... where is our galaxy (and all the other galaxies out there?) Well, here's where we reach the end of our questioning. The final answer you can give to the question, "Where are you right now?" is: Inside the universe
The universe is the term we use to describe everything that exists in the physical world. It is made up of billions of galaxies, each of which is made up of billions of stars. We can't really say what it looks like but it might look something like this (show slide).
Now, whether or not there are other universes is a question that science cannot answer at this time, although some scientists do believe that there are in fact other universes. If this is the case, we could say that our universe is inside the "multiverse".
So, to sum up... we have a universe. The universe is made up galaxies. Galaxies are made up of stars. Many stars have planets going around them. So from big to little we have: universe, galaxy, solar system, planet.
To give you an idea about where we are in the universe, we are going to watch a short film. In this film, we are going to travel very fast. What is the fastest thing in the Universe? Answer: light. We often don't think of light traveling but it does. It's just that most lights are so close to us that the light seems to appear instantly (switch the classroom light on and off to demonstrate this). But when it comes to very large distances, it takes time for light to travel. For example, it takes 8 minutes for light to come from the sun. In other words, when you look at the sun, you are not seeing it as it is right now. You are seeing what it looked like 8 minutes ago! Okay, let's start traveling at the speed of light and see what we can see. (show video)
How did the universe begin?
For many years, scientists believed that the universe had no beginning (that it had always existed) and that it was unlimited in size (that it went on and on forever). We now know that these things are not true. We now know that:
- the universe is about 13.5 billion years old
- the universe is getting bigger and bigger every day
How do we know these things? Well, we know these things because of discoveries made within the last 100 years that led to the development of one of the greatest scientific theories of all time -- the Big Bang theory. The Big Bang is the most widely accepted theory about how the universe began. To explain it, let's go back to the idea of light.
Remember that when we look at the sun, we are seeing it as it was 8 minutes ago. It's kind of like being able to see the past. Well, the stars are even further away than the sun. Many of the stars that we see at night are hundreds of "light-years" away (meaning that it took hundreds of years for the light to travel from those stars to earth).
A light-year is the distance that light can travel in one year. It is a measurement of distance, not of time. We use it for measuring really large distances in space. If we look carefully, even without a telescope, we can see a nearby galaxy (called Andromeda). It is 2.5 million light years away! At the moment, the largest telescope is the Hubble Space Telescope. It is up in the sky, going around the earth. It can see billions of years into the past! This photo (show slide) taken by Hubble, shows some of the oldest, most distant galaxies that we can see.
So, what do we see when we look billions of years into the past? Well, the further back in time we go, we see that galaxies get closer and closer to each other. This means that at some point they must have been all squished together in one tiny dot -- a very hot & heavy dot! Scientists have calculated that this was the point when the universe as we know it began -- about 13.5 billion years ago. For some reason, at that moment, the universe exploded as a "big bang" and has been continuing to get bigger and bigger every day.
To sum up, the big bang is the popular theory that the universe began as a single point about 13.5 billion years ago, at which time it exploded and started to grow bigger and bigger.