STRATA Get the app

Home / Learn

Learn anything

Free, in-depth courses — each one built by STRATA from a real learner's question. Read the opening lesson, then continue free in the app.

Business

How to sell anything to anybodyBefore the 1880s, selling was considered a talent you were born with — like having a good singing voice or a knack for card tricks. There was no…

Culture

Game theoryIn the 1920s, a brilliant young mathematician named John von Neumann loved to play poker. He was not very good at it. However, his losses led to a…How to market apps through social mediaLuis von Ahn did not begin his career in marketing; he began in computer science, famously inventing the CAPTCHA and reCAPTCHA systems. When he founded…Japan's Edo Period: Samurai Culture, Society, and TransformationImagine Japan in the year 1600. It's like a giant puzzle with pieces scattered everywhere. For decades, powerful warlords, known as daimyo, have been…

Finance

Black Swan Events and Unpredictable ImpactFor a thousand years, the Theodosian Walls of Constantinople were considered unbreakable. Think of them like a firewall that had never been hacked — not…Roll-up investmentsYou’ve explored how roll-up investments consolidate fragmented industries. Now, let’s dive into a deal that redefined how Wall Street viewed these…

General

SamuraiIn the late 700s, the Japanese imperial court in Nara — and then its new capital at Heian-kyō (modern Kyoto) — faced a stubborn problem. The northeastern…Semiotics — the study of signs and meaningAround 385 BCE, Plato wrote a dialogue called the Cratylus. It is one of the oldest surviving arguments about a question that still haunts language…What is a transistor?Before anyone had heard the word "transistor," before silicon chips ran the world, a scientist in Calcutta was doing something remarkable with crystals.…

History

Chicago Architecture and Urban PlanningPicture a wild, wet grassland where a river bends lazily into a massive lake. In the early 1800s, the place we call Chicago was a swampy marshland…FocusingIn 1953, researchers at the Chicago Counseling Center began a massive research project. They recorded hundreds of hours of therapy sessions. They wanted…Navigating AI Alignment, Safety, and Shaping the Long-TermImagine a machine that could do any calculation you throw at it. Not just add or subtract, but anything a human mind could compute. This wasn't just a…The Crusades: causes, campaigns, and consequencesImagine a vast crowd gathered on a windswept hill in Clermont, France, in 1095. Pope Urban II stands before them, his words echoing across the assembled…The Five Great Extinction Events Shaping Earth's HistoryImagine a world without trees, without flowers, without even grass. This was Earth about 450 million years ago, during the Ordovician Period. The…The Speed of Light: Physics, History, and ImplicationsFor most of human history, people assumed light traveled instantly. You open your eyes and the world is just there — no waiting, no lag. Even the great…The three body problemImagine dropping an apple. It falls to the ground. Now imagine the Moon. It orbits the Earth. Why doesn't the Moon fall to Earth, or the apple fly off…

Mathematics

Calculus from StartImagine a sculptor, centuries before calculus, trying to find the exact volume of a complex shape. How could they do it? The ancient Greeks, like…

Psychology

ADHD in adultsImagine your brain has a reward system, like a built-in encouragement machine. When you do something good for survival or progress—like eating when…L-Tyrosine and focusImagine finishing a challenging project. A wave of satisfaction washes over you. That feeling? It's partly driven by a remarkable chemical in your brain…MetacognitionYou reach the bottom of a page in a heavy book. Suddenly, you realize you have absolutely no idea what you just read. Your eyes moved over the words…Serial killers: psychology, patterns, and investigationImagine London in 1888. Gas lamps cast flickering shadows on cobblestone streets. Fog, thick as soup, clung to the alleys. In this eerie atmosphere, a…The best, natural resources for focusWhen you consume caffeine alone, your central nervous system undergoes a rapid escalation. By blocking adenosine receptors in the brain, caffeine…

Science

Black Holes and the Calculations that support themImagine a world where light itself can fall. In the late 1700s, scientists thought of light as a stream of tiny, solid high-speed bullets. They called…Human BalanceImagine a creature with no jaw, no spine, and eyes buried under skin. This is the hagfish, a living fossil. To understand how you stay upright, you must…Spaced retentionImagine you wake up one morning and can't remember your own name. Or the face of the person beside you. This isn't a nightmare; it's a terrifying…

Technology

From Zero to 1000: Your App's First DownloadYou just executed a flawless app launch. The code is perfect and the design is beautiful. But right now, your app is a luxury store in a desert. Unless…How to scale an app to millions of MAUImagine walking into a restaurant where the menu is fifty pages long. You feel overwhelmed. You might just order a glass of water and leave. In 2010,…Hyperscale Data Center CommissioningImagine a world where every calculation, from weather forecasts to military trajectories, was done by hand or with mechanical aids. This was the reality…

← Home© STRATA · Koa Tech App Studios