Why this exists

I couldn't find anywhere good to learn this.

I took AP Calculus BC, and the whole time I was studying for it I could never find a website that actually helped.

It was always review videos. Someone works through their problems on a whiteboard, and you either follow along or you don't — and if the thing you're stuck on isn't the thing they happened to pick, you're on your own. None of it was tailored to me, or to what I was actually struggling with.

And there was no way to picture any of it.

Calculus is about things moving and changing. It kept being handed to me as a page of symbols.

A curve doing something is a completely different object in your head than the formula that describes it. I wanted the first one and kept being given the second.

Summer, after the course

So I built Unit 10 first — for fun.

Sequences and series. No plan behind it, I just wanted to see convergence actually converge instead of reading that it did.

Then I realized I could build the whole thing.

So I kept going until the entire course was done.

Every lesson is built around something you can move rather than a diagram you look at. And because the thing I hated was that nothing was tailored to me, the two biggest features work on your problem: the Visualizer draws whatever you paste in, and the mock exam grades what you actually wrote.

What's next

Now I'm off to study mechanical engineering.

I built this the summer before starting college in Miami. It stays online, and it stays free.

No account, no ads, no email wall, nothing to buy. If it's useful, tell someone in your class. That's the whole business model.

It won't be perfect.

One person built this, so there will be mistakes in it. If you find a wrong answer, a broken graph, or an explanation that doesn't make sense, I genuinely want to know — that's how it gets better.

Found something wrong? Email me.

— Christian Grosso