The Exploratorium celebrated its "Big 40" this past weekend and allowed free admission and showcased a unique set of exhibits.

The museum was filled with people of all ages who enjoyed what has made the museum a San Francisco staple for nearly half a decade: an interactive learning experience.

"It's a hands-on museum. There's not too many museums out there that actually let you touch the exhibits and play with the exhibits," said employee Marcus Ante as he looked around the museum with enthusiasm, much like the many children who come through the building daily.

Ante started working at the Exploratorium as a high school explainer two years ago. Unlike many people who become bored with a job after a couple of years, he is still excited to put in hours at the museum.

One exhibit in particular, Cutting Ice Into One, received significant attention from visitors.

"People are really excited about the motorcycle, said Kathe Traynor, who has volunteered at the museum for the last two and a half years. "The weight of the motorcycle drags through the wire and through the block of ice, which will remain intact."

The idea behind the exhibit is to see the motorcycle slip from the block of ice gradually. The ice not only remained intact, but the wire which held the motorcycle leaves behind a visible trace from where the ice melted and froze in place as the wire moved.

"One of the great things [about the anniversary] are the tours that we're offering so people can see some things that you may otherwise never have an opportunity to see or experience here," Traynor said.

Though the birthday weekend was exceptional because of its free admission, the events will continue for the month of November.

"This weekend are the two free days for the actual 40th," Traynor said. "There are other events. I know next weekend K.C. Cole, who wrote the book about Frank Oppenheimer, she'll be speaking." Oppenheimer is the scientist who founded the museum in 1969.

Another favorite this weekend was the bubble mania that spread through the museum. In addition to Tom Noddy's bubble magic performance, children ran outside hunting down bubbles larger than most beach balls.

Stirling Johnson, a bubble blowing savant, stood at the entrance of the museum with a contraption which resembled a commercial fishing net more than a bubble wand.

"I got into bubbles in high school because of a science project," Johnson said. "I don't even remember what the project was." He laughed as he realized the irony in his statement.

Outside Johnson teaches the children how to use the tools to make larger-than-life bubbles. In true Exploratorium fashion, the children took their lessons and applied them.

"It's just a perfect opportunity to reach out to different people and learn from each other," Ante said about the museum.