In the 1920s, chemists searching for a solution to engine knock helped create one of the most widespread public health disasters in history. Leaded gasoline promised smoother-running cars and bigger profits, but at a cost that would not be fully understood for decades. In this episode of The Mistakes That Made Us, Stephanie Einstein Tashiro traces the rise of tetraethyl lead from a celebrated technological breakthrough to a global environmental contaminant. Along the way, she explores the scientists who warned of the dangers, the children whose lives were affected by lead exposure, the battle to remove lead from gasoline, and the legacy that still lingers in soil near roads and cities today. It is a story of innovation, unintended consequences, and how one decision can shape generations.

A naval engineer trying to stabilize equipment during World War II accidentally knocked a spring off a shelf and watched it “walk.” That mistake became the Slinky, one of the most recognizable toys in American history. But the real story goes far beyond the invention itself. In this episode, we explore the physics behind the Slinky’s strange motion, the rise of the toy as a cultural icon, and the remarkable story of Betty James, the woman who rescued the company when it was on the verge of collapse.

In 1945, a melted chocolate bar in an engineer’s pocket set off a chain reaction that would transform kitchens around the world. This episode tells the surprising story of Percy Spencer and the invention of the microwave oven—from its origins in military radar technology to its role in reshaping how (and what) we eat. Along the way, we clear up common misconceptions about microwave radiation, explore the rise of the TV dinner, and examine how a once-skeptical public came to embrace one of the most misunderstood appliances in modern history.

In 1968, 3M chemist Dr. Spencer Silver set out to create a powerful new adhesive for aircraft. What he ended up with was… not that. Instead, he developed a glue so weak it could be peeled off and reused without leaving a trace. For years, no one knew what to do with it—until a frustrated choir singer named Art Fry needed a bookmark that wouldn’t fall out of his hymnal.

In this episode of The Mistakes That Made Us, Stephanie Einstein Tashiro explores how an adhesive that failed its mission ended up revolutionizing communication, office culture, and paper. From yellow scraps of paper borrowed from the lab next door to a failed product launch in four cities, this is the story of persistence, innovation, and a little bit of luck. Plus, what happens when your world-changing invention belongs to your employer?