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The Big Bang
What was there before the universe existed, and how could something come from nothing?

Everything in our universe (every star, every atom in your body) began from a single, infinitely tiny point billions of years ago. In this lesson, your learner will discover the Big Bang: not as a loud explosion in space, but as the incredible moment when space itself began to expand. It's a story of beginnings that starts from almost nothing and creates everything.

S2S_Lesson01 by Selene

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Key Ideas

  • Everything began with the Big Bang. It is the moment space, time, and matter all started at once.
  • The Big Bang was a big stretch, not a loud explosion, and things in space are still getting farther apart.
  • We know the Big Bang happened because scientists saw evidence like background radiation and how galaxies are moving away from each other.
  • Scientists currently think time itself may have begun with the Big Bang.

Spines

  • DK Science pg. 112-113

✏️  Notebooking Activity               
Draw and label a diagram showing the Big Bang moment (the singularity) and then the resulting expansion. Label how long ago each part was.

VocabularyUniverse — Everything that exists — all matter, energy, space, and time taken together as a whole.
Big Bang — The moment about 13.8 billion years ago when all of space, time, and energy began expanding rapidly from an incredibly hot, dense point.
Singularity — The tiny, unimaginably hot and dense point from which the universe began expanding at the Big Bang.
Expansion — The ongoing process by which space itself continues to stretch and grow, carrying galaxies farther apart over time.
Cosmic Background Radiation — Faint heat energy left over from the Big Bang that still fills the universe today — evidence that the Big Bang happened.
Energy — The ability to do work or cause change; the first moments of the universe were pure energy before matter formed.

Discussion Questions
1. What was the universe like before the Big Bang?
Sample Answer: “There was nothing, no planets, no stars, no space.”

2. Why was the Big Bang not like fireworks or a balloon popping?
Sample Answer: “Because it wasn’t loud and it didn’t happen in just one place.”

3. What happened right after the Big Bang began?
Sample Answer: “Space got bigger, time started, and tiny bits of stuff moved around.”

Digging Deeper

4. What do scientists think the universe was like before the Big Bang? 
Sample answer: There was no space, no time, and no matter, basically, nothing existed the way we understand it.

5. Why do scientists believe the universe is still expanding today? 
Sample answer: Scientists see galaxies moving away from each other, like dots on a balloon getting farther apart as it inflates. They also notice red shift in light and leftover radiation from the Big Bang, called cosmic microwave background.

6. If you could witness the very first moment of the Big Bang, what might you experience? 
Answers will vary dramatically

Cosmic Calendar
Where we are: January 1 · Midnight
This is the first time learners will see the Cosmic Calendar. Read the introduction below in full, then move into today’s lesson.

Read aloud: 
Before we dive into today’s lesson, I want to introduce something we’re going to use all year long. It’s called the Cosmic Calendar. Here’s the idea. The universe is about 13.8 billion years old. That number is so enormous that it’s almost impossible to imagine. So scientists and teachers have come up with a way to shrink it down into something our brains can actually picture: one single calendar year. On this calendar, the very beginning of the universe, the Big Bang, happened at midnight on January 1st. And right now, today, all of modern human history is crammed into the last few seconds before midnight on December 31st. Every month on this calendar represents about 1.15 billion years of real time. Every single day is about 37.8 million years. Every hour is more than a million years. At the start of each lesson this year, we’re going to look at this calendar and I’m going to show you exactly where we are in the story. We’ll mark the moment we’re studying, and as the year goes on, you’ll watch our marker move through the calendar and start to feel just how enormous time really is. So where are we right now? Right here, January 1st, midnight. The very first moment on the calendar. This is the Big Bang, the beginning of everything, and that is exactly where we’re starting today. Keep this image in your mind. By the end of the year, we’ll have traveled all the way from this first moment to just seconds before midnight on December 31st. Let’s get started.
Timeline PageThe very first page in your timeline should be labeled “The Big Bang: 13.8 Billion Years Ago”. The workbook prompt asks learners to draw a single blazing point of light at the center of the page with waves of energy and light exploding outward in every direction. Remind them: no stars yet, no planets: just pure heat and expanding space.

SCIENTIST SPOTLIGHT: Chanda Prescod-WeinsteinChanda Prescod-Weinstein is a theoretical physicist and cosmologist whose work focuses on dark matter, the early universe, and a concept called axion physics. She is one of the few Black women to hold a faculty position in theoretical physics in the United States, and she has been outspoken about the barriers that Black and Indigenous scientists face in academic science. Her book The Disordered Cosmos weaves together particle physics, cosmology, and social justice in a way that is accessible and bold. Learners can connect her work to the question at the heart of this lesson: what can we actually know about how the universe began, and who gets to ask those questions?

Videos:


Books:
Digging Deeper Activity:
Prescod-Weinstein writes about how science is shaped by who is allowed to do it. What might we be missing in our understanding of the universe because certain voices have been left out? Write a short reflection or discuss as a family.

Sources and More Information:

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