Big Course: Year 4

Another whirlwind adventure

Welcome to Year 4 of our Big Course.

Live classes (seminars and webinars) will begin the week of September 14th, 2026.

Or, you can start streaming recordings for Year 4 on September 20th.

To catch up on Years 1, 2 and 3, check out our past recorded topics.

Grab a seat
Catch up on previous topics

From our inbox

“We so appreciate your approach and your work and time that you put into these incredible lessons!

We talk about Brandon often in our house, and my kids feel like they know you and they trust you. I firmly believe education is best achieved in relationship, so that is very important to me.

In addition, I appreciate that you don’t shy away from tough topics and you don’t see anything as off limits within developmentally appropriate reason...this is how we operate in our home, and I think it’s the best way for kids to learn that nothing is bad or wrong unless we designate it as such. So thank you for all your work and everything you do!”
— Becca H.
Hear more from parents

The six topics

Topic 19:
The Sun is Weird

 
 

In which we see everything in light of the big glowing ball in the sky

Ah, the Sun! We see nothing without it… but we don’t really see it at all. And what it is is much weirder than you might think: what’s going on in there is so strange that physicists had to invent new ideas to explain it. We’ll peer inside the Sun to talk how it was born, how it will die, and how, in the meantime, using its light might save us all.

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Topic 20:
Soaps are Weird

 
 

In which we get down and dirty with cleaners and chemistry

Soap, bleach, alcohol, ammonia… we’ve got a whole arsenal of cleaners under your sink, but most of the time, we grab the wrong one! Each destroys gunk in a completely different way. This month, you’ll learn the (surprisingly ancient) stories of human cleanliness so you can take on the stickiest messes. Most of all, we’ll use cleansers to explore one of the most important questions in chemistry: what is a chemical bond, really?

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Topic 21:

Guts are Weird

 
 

In which we digest a bunch of intestinal information

You are — and we mean this respectfully — a tube with legs. Food comes in one end, poop comes out the other, and in between is what you call “being alive”. How’s it all work? We’ll trace the journey food makes through your basic gastro-intestinal tract. You’ll learn to read your excrement, and come to terms with the trillions of tiny creatures who call you “home”. By the end, you’ll understand the fundamentals of nutrition, and have earned an opinion on some actually controversial questions, like “is high-fructose corn syrup bad?”

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Topic 22:
Dirt is Weird

 
 

In which we dig deep and unearth the secrets of the soil

“Dirt” is almost a dirty word. It gets no respect. And yet without, most life on land couldn’t exist. Why’s it so special? You’ll learn what plants actually need from it, and whether organic fruit is actually worth the money. You’ll shrink down tiny to discover different worlds in different soils. You’ll see how misunderstanding dirt has led to disasters, and how one man’s insight literally saved billions of people from a slow death. Along the way, you might even learn a few things that will help you become a better gardener!

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  • Coming soon!

Topic 23:
Onions are Weird

 
 

In which we peel back the layers… and the layers fight back

An onion isn’t “a plant”! Here, we’ll bring together physiology, chemistry, and evolution to understand what an onion really is, and how the whole plant family tree hangs together. We’ll find what “spicy” actually means (it’s probably not what you think), and what happens the instant your knife slices through an onion’s skin.

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Topic 24:
Mosquitoes are Weird

 
 

In which we see through the compound eyes of Earth’s deadliest animal

We all feel like we understand mosquitoes, and we’re all wrong. This month, you’ll shrink down to see what one actually looks like, and how she experiences the world — how she sees, hears, smells, tastes, and feels. You’ll trace her ancestry through the invertebrate “half” of animals — that is, the 97% of animals without bones. You’ll find out why mosquito bites itch, and how to cure them instantly. Finally, we’ll all wrestle with a genuinely hard moral question: as we gain the power to drive them extinct, should we?

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Watch an open house

Year 4 FAQ

  • Probably! We design our lessons to link up together. That said, you could do the live lessons of this year AND blast through Year 1's recordings on your own.

  • In Year 1, we aimed for ages 8–15; in Year 2, we're aiming for 9–16.

    But we have some kids older and younger than that, too. (Sometimes adults sign up for themselves!)

  • Usually a bit more than 90 minutes in total, broken up into 20–30 minute chunks.

  • For as long as your subscription lasts, or permanently if you purchase a topic outright.

  • Usually just a notebook — we recommended a dotted one, like this or this. We'll let you know when you'll need additional materials (usually it's stuff lying around the house).

  • Actually, these are the same thing as the live webinar — just lightly edited for your viewing pleasure.

  • Quite a few: see our Discounts page.

  • We can try! See our “help us become a vendor” page.

  • Loads of people! See “Why You Might Hate Us.” (But remember our Ridiculous Guarantee.)

  • Feel free to use it with everyone in your family! (You don’t need to purchase it multiple times.)