Construct — don't memorize

Most math apps quiz you.
This one makes you explain it back.

Build Understanding teaches the math, then hands you a curious AI student who asks why every step works. If you can't answer, you didn't really learn it. That's the whole pitch.

buildunderstanding.com / teach-it
α
Teach It
Definition of the Derivative
Change topic
AP Calculus AB · 2.1
45Clarity
35Depth
70Accuracy
PHASE 2/6
Foundations
ALEX
Can you give me the one-sentence version of what a derivative actually IS? Just so I know what we're solving for.
It's the slope of the tangent line at a single point. The instantaneous rate of change.
ALEX
Wait — if a tangent only touches the curve at one point, how do you compute a slope from one point?
ALEX
Explain the concept to Alex…
Teach It · 2.1 Definition of the Derivative
11Courses445Topics285Builds
· One loop · Three modes ·

Read it. Build it.
Then teach it back.

The whole product is one loop, three artifacts. Here's what each looks like in the app.

01Read

You read.

The notes ask before they answer. Most pages pause to make you predict what's next. Written to be read at human speed, not skimmed.

· READ · 2.1 Definition of the Derivative

Suppose we want to know how steep a curve is at one particular point. Not the average slope between two points — that we know how to compute — but the slope right here, at this instant.

Here’s the trick. Pick a second point a tiny distance h away. Compute the average slope between the two. Now shrink h.

Pause before scrolling
What happens to the difference quotient as h approaches zero?
· BUILD IT · Derive d/dx [x²]
 
HintWhiteboardStep 5 / 7
02Build

You build.

Step by step, you derive the result. Type each algebraic line. Green check when it's right. Hints unlock if you ask.

03Teach

You teach.

An AI student named Alex asks naïve questions about the topic. Fumble the explanation and your Clarity score tells you exactly where it broke down.

buildunderstanding.com / teach-it
α
Teach It
Definition of the Derivative
Change topic
AP Calculus AB · 2.1
45Clarity
35Depth
70Accuracy
PHASE 2/6
Foundations
ALEX
Can you give me the one-sentence version of what a derivative actually IS? Just so I know what we're solving for.
It's the slope of the tangent line at a single point. The instantaneous rate of change.
ALEX
Wait — if a tangent only touches the curve at one point, how do you compute a slope from one point?
ALEX
Explain the concept to Alex…
· 11 courses · 445 topics ·

Algebra 1 to Multivariable.

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· Pricing · Free forever ·

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