Today’s puzzles challenge your engineering knowledge with real-world examples. In a cranberry sorting facility, thousands of cranberries fall onto a board every minute. Good cranberries are firm and bounce, while bad ones are soft and don’t. Engineers use this simple principle to separate the good from the bad—only the bouncy cranberries are collected, while the soft ones fall through. This method is efficient, cost-effective, and relies on basic physics. In the United States, medicine bottle caps are designed to be child-resistant, but not child-proof. These caps are engineered to be secure against 85 percent of children under five. While this may seem low, it reflects a balance between safety and accessibility for adults who need to open the bottles. The design aims to prevent accidental ingestion by young children while still allowing caregivers to access the medication when needed. In 2020, engineers replaced the pedestrian handrail on the Golden Gate Bridge to improve safety during high winds. The original design used metal balusters shaped like the letter "H," creating a pattern that looked like "HHHH..." with each horizontal bar 10 centimeters wide. The new design uses thin vertical slats, making the pattern look like "IIII..." with each slat only 0.6 centimeters wide. The goal was to reduce wind resistance, but this change led to two serious unintended consequences, highlighting the complexity of engineering decisions. Cabin air pressure in airplanes is carefully controlled to match the pressure at ground level. As a plane flies, the air pressure outside drops significantly, creating a large force pushing outward on the cabin walls. In the early 1950s, several planes crashed mid-flight when the fuselage ripped apart due to this pressure difference. To address this, UK manufacturer de Havilland developed a way to test the pressure integrity of its Comet jet—then the world’s first commercial jet—without flying it. This innovation helped ensure the safety of future air travel. The author of today’s puzzles, Alex Davies, is a technology reporter and the author of How to Keep a Plane in the Sky, a book exploring the world of test engineering. The book delves into the stories of scientists and engineers whose work ensures that objects like planes, bottles, and bridges remain safe and functional. Recently, Davies was awarded the 2026 Christopher Zeeman Medal, a top honor for mathematics communication in the UK. He has been setting puzzles on alternate Mondays since 2015 and invites readers to submit their own puzzles for future features.