Other people's interaction design wisdom, so that we're not re-inventing the (scroll) wheel!
"Lean UX replaces requirements statements with testable statements of assumptions. Instead of writing a requirement that says, the site shall incorporate shopping cart functionality, Lean UX teams might say, we assume that a shopping cart is the best way to structure the e-commerce flow on our site. Instead of solutions then, requirements are transformed into questions that teams can ask (and must answer) about their business. Progress is measured in terms of validated learning, rather than features implemented."