Education — Build Your Own Systems With AI

Build with AI (free)

• Start With What AI Is Actually Good At

  Most people who say AI is overhyped gave it the wrong job. This first free lesson covers the single shift that changed how we build: match the job to the right tool, and never force a hard job through a weak one to save a step.

• Cheap First, Escalate On Purpose

  You do not need the most powerful model for every task. This lesson covers the ladder we built into our own AI: a cheap fast tier for simple work, a default tier for normal work, and a top tier only for the genuinely hard cases.

• Make It Cheap Enough To Leave Running

  A tool you cannot afford to run all day is not really a tool. This lesson covers the cost math that surprised us: the bill scales with how much text you push through, not how many tasks you run.

• What Is a High-Yield Savings Account, and Why the Rate Is Only Half the Story

  A high-yield savings account is an ordinary savings account that pays a market-linked rate instead of a token one. This lesson covers how they work, what the insurance actually covers, and the two things the headline rate hides.

• How Big an Emergency Fund Actually Is — The Arithmetic Behind Three to Six Months

  Three to six months is the guideline everyone repeats and almost nobody unpacks. This lesson covers what the number is actually measuring, why it is expenses and not income, and the general factors that push it up or down.

• Debt Snowball vs Avalanche — The Math, the Psychology, and Why Both Work

  Snowball pays smallest balance first. Avalanche pays highest rate first. One wins on arithmetic, one wins in behavioral studies, and the difference between them is usually smaller than the difference between starting and not starting.

• The 50/30/20 Budget — What It Is, Where It Came From, and Where It Breaks

  Fifty percent needs, thirty percent wants, twenty percent saving and debt. The 50/30/20 rule is popular because it is simple. This lesson covers what each bucket actually contains and the cases where the ratios stop describing reality.

• Zero-Based Budgeting — Giving Every Dollar a Job Before the Month Starts

  In a zero-based budget, income minus everything assigned equals zero. Nothing is left floating. This lesson covers the mechanics, the reason the method is powerful, and the honest cost in effort that makes many people drop it.

• What an Index Fund Is — And Why Low Cost Is the Whole Argument

  An index fund holds every stock in a list, by formula, with no manager picking winners. This lesson covers what that buys an investor in diversification and cost, and what it explicitly does not promise.

• ETF vs Mutual Fund — Same Idea, Different Plumbing

  An ETF and a mutual fund can hold the identical basket of stocks and still behave differently in an account. The differences are plumbing: how they trade, what they cost to enter, and how taxes flow through.

• Compound Interest — The Arithmetic That Rewards Starting Early

  Compounding is interest earning interest. The mechanism is simple; the consequences are not intuitive, which is why the same arithmetic that builds savings quietly is the arithmetic that makes card debt so expensive.

• APY vs APR — Two Acronyms, Two Directions, One Compounding Difference

  APY includes compounding. APR does not. That single difference explains why savings products advertise one and loans advertise the other, and why comparing a number of one kind against a number of the other kind is a category error.

• Sinking Funds — Turning Predictable Surprises Into Line Items

  Car registration, holiday gifts, annual insurance, the aging water heater. None of these are surprises, yet they keep landing like emergencies. A sinking fund converts each one into a small monthly line item ahead of time.

• Index Funds vs ETFs — The Overlap Is Real, the Differences Are Structural

  An index fund and an ETF can hold the identical indexed basket, so the real comparison is between two wrappers, not two strategies. This lesson separates the strategy question from the structure question and covers what the wrapper actually changes.

• Roth vs Traditional — Paying the Tax Now or Later

  A Roth and a traditional retirement account share the same untaxed growth engine and differ on one axis: whether the tax is paid now or in retirement. This lesson covers the trade-off, the details that shift it, and why nobody can optimize it with certainty.

• The HSA and Its Triple Tax Advantage — The Account With Three Breaks

  A health savings account is taxed favorably at three separate points, which is why it is called a triple tax advantage. This lesson covers the three breaks, the rollover feature that turns it into a long-horizon vehicle, and the strict eligibility rule.

• Dollar-Cost Averaging — Buying on a Schedule Instead of a Hunch

  Dollar-cost averaging invests a fixed amount on a fixed schedule regardless of price. This lesson covers the mechanical effect on average cost, why the main benefit is behavioral, and the honest limits the method does not escape.

• Bond Basics — Lending Money on a Known Schedule

  A bond is a loan with a schedule: interest at set intervals and principal returned on a stated date. This lesson covers the three numbers that describe a bond, why its price moves opposite to interest rates, and the risks that remain.

• Expense Ratios — The Fee That Compounds Against You

  An expense ratio is the annual fee a fund charges as a percentage of what is invested, deducted quietly rather than billed. This lesson covers how small percentages compound into large sums, why index funds sit low, and where the number is disclosed.

• Portfolio Rebalancing — Selling High and Buying Low by Rule

  Rebalancing returns a portfolio to its intended mix after growth pulls it off target. This lesson covers why drift raises risk without a decision, why rebalancing runs in the unglamorous direction, and the calendar and threshold triggers used to do it.

• Asset Allocation by Age — Matching Risk to Time Horizon

  Asset allocation is the split of a portfolio among stocks, bonds, and cash, and age enters because time horizon shapes how much short-term swing a portfolio can absorb. This lesson covers why horizon drives the mix and why the age rules of thumb are only a sketch.

• How a 401(k) Employer Match Works — and Why It Is Usually the First Dollar to Capture

  An employer match is compensation your employer adds when you contribute your own pay, but only if you contribute enough to trigger it. This lesson covers the common formulas, the threshold that captures the full match, and how vesting works.

• What After-Tax Yield Actually Is — Why the Quoted Rate Is Not the Kept Rate

  After-tax yield is the interest you actually keep once tax is taken out. This lesson covers why the quoted rate overstates what you keep, the basic arithmetic, and why after-tax yield can reorder which account is really better.

• Sinking Funds vs an Emergency Fund — Two Different Jobs for Your Cash

  A sinking fund and an emergency fund are both cash you set aside on purpose, which is why they get confused. This lesson covers the different job each does, how each is sized, and why keeping them separate protects your buffer.

• Money Market Funds vs High-Yield Savings — and the Account That Shares the Name

  Comparing a money market option with a savings account often means comparing three products that share overlapping names. This lesson sorts out which are bank deposits, what protects each, and how they differ on yield and access.

• CDs vs High-Yield Savings — Locking a Rate Against Keeping It Liquid

  A certificate of deposit and a high-yield savings account are both insured bank products for cash. This lesson covers the real choice between them: locking a fixed rate for a term versus keeping your money reachable at any time.

• What Is a Treasury Bill (T-Bill) and How It Works

  A Treasury bill is a short-term loan to the US government sold at a discount to face value. This lesson covers how the discount works, the short maturities, how you buy them, and why their tax treatment can change how they compare with a bank account.

• I Bonds vs a High-Yield Savings Account

  I bonds and high-yield savings accounts are both called safe, but they handle time very differently. This lesson covers the I bond lockup and penalty, the inflation-linked return, tax deferral, and when a liquid savings account fits instead.

• Traditional vs Roth 401(k): How the Two Differ

  A 401(k) can hold traditional or Roth contributions, and the difference is entirely about when the money is taxed. This lesson covers pre-tax versus after-tax, why the employer match is traditional, and how the choice actually gets framed.

• Treasury Bills vs CDs: How They Compare

  T-bills and CDs both pay a fixed return over a set term, but they differ in issuer, insurance, how you exit early, and tax treatment. This lesson walks through all four, including the state-tax exemption that can flip the comparison.

• What Is FDIC Insurance and What It Actually Covers

  FDIC insurance is why an insured bank deposit is treated as safe. This lesson covers the standard coverage limit and how its three dimensions work, what is covered versus what is not, the NCUA equivalent for credit unions, and common ways to stay fully covered.

• What Is a CD Ladder and How It Works

  A CD ladder staggers certificates of deposit across terms so a rung matures on a regular schedule. This lesson covers how the rungs work, why the structure balances access against commitment, and the tradeoffs to be honest about.

The premium library

• The Wall Everyone Hits — AI Forgets Everything Between Chats

  The wall almost everyone hits is that the model starts from zero every session. It cannot remember your project, your decisions, or last week's fix. The lever is memory and context, not a smarter model.

• Two Reviews, Or It Is Not Done

  One review from something other than the builder, and one measured check of the real result by you. The failure mode is making review optional depending on your mood.

• Why We Built Tephra — Our Shared Memory, and Why It Is the Shortcut

  Every lesson in this section was a wall we hit. A shared, curated memory of the lessons, the playbooks, and what actually worked means the next person does not start from zero.

See the full premium library

The money framework

The redundancy-first foundation lives in the free intro lessons. Membership and the weekly cadence are on the pricing page.