In 1934, 29 American secondary schools agreed to participate in a landmark study to determine whether high schools could better serve youth when given flexibility around curriculum and freedom to "experiment with the basic structure of schooling." Popularly known as the "Eight-Year Study," it bolstered movements for progressive education, which encouraged student-centered, hands-on, and active learning instead of teacher-led lectures, standardization, and rote memorization. But a key lesson from the study was missed: How we assess knowledge also needs a radical shift. The United States has placed a disproportionate focus on and investment in standardized tests, even in the early grades. U.S. federal law (most recently, the 2015 Every Student Succeeds Act) requires states to deliver end-of-year English language arts (ELA) and mathematics tests in grades 3 through 8. The United States still needs to learn some key lessons from the Eight-Year Study almost 90 years later. We must embrace assessment models that bolster a wider set of social and interpersonal skills, allow creative ways to demonstrate those skills, and encourage students to work at their own pace.