On Caltech’s ‘Ditch Day,’ they make a science out of shenanigans

Wearing an ear-to-ear smile and her hair slightly frizzy from her helmet, Caltech junior Curie Ahn craned her neck toward the sky, her eyes still wide from the adrenaline.

“I was actually pretty terrified,” the biology major said. “I’m a little bit afraid of heights.”

Afraid or not, Ahn didn’t have much of a choice when the senior class gave her the task of rappelling about 60 feet down the side of one of the school’s buildings Friday. It was “Ditch Day” at Caltech, and overcoming the senior class obstacles is tradition.

PHOTOS: ‘Ditch Day’ at Caltech

Caltech officials said the Ditch Day ritual goes back almost a century. Classes at the Pasadena campus are canceled and seniors plan for weeks and months before the day finally arrives.

Yet for a school that embraces the exactitude of math and science, the details around how it all began are fuzzy.

According to the campus website, sometime during the 1920s, weary Caltech seniors decided to give themselves a break and headed off campus for a day. The next year it was repeated and embraced as a tradition: a ditch day for seniors only. Underclassmen were not to know about it.

But secrets don’t remain secrets for long, especially within the tight-knit Caltech community. Freshmen, sophomores and juniors eventually clued in.

And with the seniors away, the underclassmen play.

Over the years seniors have returned to campus to find their rooms filled with sand, a working car, a functioning cement mixer and furniture glued to the ceilings. In response, seniors began stacking concrete blocks in front of their doors when they headed off campus.

Concrete blocks gave way to elaborate puzzles, which turned into a day of challenges for underclassmen — and poor Curie Ahn rappelling down a school building.

Each challenge leads to another clue. There’s no prize at the end, just a healthy brain workout. Challenges range from decoding chemical reactions to water-balloon fights.

PHOTOS: ‘Ditch Day’ at Caltech

About 100 yards west of the rappelling, seniors Cassie Lochhaas and Vivian Zhang were working 100 pounds of cornstarch into a 4-by-4-foot pool of water.

Here’s a fun science fact: A proper mix of cornstarch and water makes an oozy creation that loses viscosity the faster you move through it.

With that in mind, Lochhaas and Zhang hid a number of clues leading to the underclassmen’s next challenge on pieces of paper sealed in little baggies inside the pool. With their hands secured behind their backs, the underclassmen must pull the clues out with their feet. The challenge: Don’t move too fast or the cornstarch-water mix will thicken.

“After two, three years, you start to appreciate the elegance of the puzzles,” said Zhang, her jeans stained and arms coated in white ooze up to the elbow. “There are some really creative people here who come up with some really good puzzles.”

joseph.serna@latimes.com