POMONA - Cal Poly Pomona students often learn by doing. On Wednesday, 80 engineering students learned by destroying.

Two sections of a sophomore-level engineering course designed foot-long bridges out of balsa wood to see how much stress the structures could endure before breaking.

"It gives you hands-on experience, you actually use what you're learning in class," said student Jessica Carter, 19. "It's practical, plus it's fun."

As the student teams one by one hung one-pound and two-pound weights to their wooden bridges, an ensemble of young engineers were busy discussing their designs and tallying their results to see who would get bragging rights after all the projects were reduced to kindling.

The only moment of silence in the bustling classroom came when student Kit Wong, 21, of Los Angeles placed a whopping 43 pounds of weight on his bridge. He ran out of weights, so he had to attach a bucket and fill it with sand.

Some of the other bridges collapsed under 10 pounds or less.

Wong and his teammate spent 10 hours on the bridge, which was intricately designed with four frames, arch support and trusses.

One engineering student said he would drive his car on Wong's bridge, another student said the two tables hosting the bridge during demolition would break first.

Professor Jawa Mariappan instructed his students to design a skywalk - a bridge connecting two buildings. The students had to use the same materials and were required to make their bridges one foot long.

"They are not going to build a (full-size) skywalk, it's too costly," Mariappan said. "But, they do learn something."

The engineering professor said this task of applying what the students are leaning will help them gauge if they are ready for the next level of engineering studies.

After the students tested their bridges, they had to calculate the efficiency of their structures and examine if they guessed correctly where the models would break first.

"This is absolutely wonderful," said Ian Stewart, director Faculty Center for Professional Development, who stopped by to watch the playful destruction. "It is just a really good example of Cal Poly's "learning by doing' philosophy."