San Francisco is home to many of the hottest technology firms in the world - companies like Airbnb, Fitbit, Lyft, OpenTable, Pinterest, Salesforce, Slack, Trulia, Twitter, Uber, Yelp, and Zynga. So it may surprise you to learn that San Francisco Unified School District no longer offers Algebra I to eighth graders.

What? How is this possible? And why would they do this?

Turns out, the case for early teaching of Algebra isn't as clear-cut as one might think. California began a push to make Algebra I the benchmark for 8th grade mathematics beginning in 2008. Some districts implemented the plan more quickly than others, giving researchers the opportunity to compare the results of students in schools that did make the move, with those that didn't. And compare they did. Researchers from North Carolina State, UC Irvine, and Stanford University concluded in a study titled Aiming High and Falling Short that "...enrolling more students in advanced courses has negative average effects on students’ achievement...", at least with respect to Algebra I and eighth-graders in California.

Why? It turns out that there are many factors beyond just the curriculum that combine to provide the value previously thought to come from studying algebra early. Things like a smaller, motivated, prepared peer group, and an experienced teacher. Take those things away by making everyone take the class, and the results aren't the same.

For more details, check out this piece in Priceonomics.