This is your companion to PSY 220 — a place to go deeper on the big ideas. Each unit builds out the mechanisms behind the concepts, pushes on the evidence, and lets you test whether it actually stuck.
Hi — I'm Bodhi. I grow a little every time you learn something, so I'm rooting for you (plant pun intended). I'll pop up in each unit to flag a common trap, connect two ideas that are easy to keep separate, or point out where the science is still being argued over. Water me with curiosity.
We move from how the idea of "adolescence" was invented → the biology underneath it → the mind and identity it produces → the risks and systems that press on it. Each tile is a full companion page with deep-dives, interactives, current 2024–2026 data, and a quiz.
How a life stage got built by factories, schools, and child-labor laws — and what "storm and stress" really means.
How developmental science actually knows things — plus Freud, Erikson, Piaget & Vygotsky, minus the myths.
The HPG axis, why puberty keeps arriving earlier, and why timing matters more than the event itself.
From Mendel's peas to polygenic scores — and the famous "depression gene" that didn't replicate.
The "Ferrari engine, bicycle brakes" model — how much of it holds up — and the biology of the teen night owl.
Sex vs. gender, the theories that explain difference, and how to read contested statistics honestly.
Record-low teen births, the shift to enthusiastic consent, and sexuality in the age of the deepfake.
Haidt's case — and the researchers who push back. Weigh the evidence for yourself.
Why teen drug use is at historic lows even as anxiety climbs — the risk paradox of this generation.
The impairment rule, differential diagnosis, and reading the 2024 "first improvement" data with care.
Roper to Jones v. Mississippi, hot vs. cold cognition, and why teens confess to crimes they didn't commit.
The war-zone myth, Baumrind's styles, and the monitoring twist: it was the teens talking, not the parents watching.
Cliques vs. crowds, the two kinds of popular, and why teens take twice the risks when friends are just watching.
Stage–environment fit, expectancy × value, and the honest numbers behind growth mindset and belonging.
These pages add the terrain behind the big ideas — the mechanisms, the connections, and the "how do we actually know this?" behind each claim.
Where scientists disagree — screens and mental health, dual-systems, candidate genes — you'll see both sides and learn to judge the evidence, not just memorize a verdict.
Every unit ends with a quiz that rewards understanding over recall, plus flip-cards and interactives so the ideas move from page to memory.
Statistics on this site were checked against current primary sources (CDC/YRBS 2023, Monitoring the Future 2024–25, CDC NCHS births, the Williams Institute, and the U.S. Supreme Court). Where a number is genuinely moving or contested, the page says so instead of pretending it's settled.