On the edge of Antioch's Deer Valley High campus, students gathered after school to toss scarves, balls and rings.
And, of course, juggling clubs.
"I didn't think it was possible to juggle well, (but) it's easy," said 15-year-old Cameron Gilbert, whose curiosity prompted him to join the school's juggling club about six weeks ago.
The extracurricular fun is provided courtesy of math teacher John Dobleman, who began teaching students how to perform sleights of hand when he arrived at Deer Valley High nine years ago.
Dobleman, who took up the diversion in 1974, estimated that he has taught 1,000 young people in his 22-year teaching career.
When youths tell Dobleman they can't juggle, he invokes one of the club's only rules -- the requirement to add "yet" to the end of the statement.
The uninitiated mistakenly assume that juggling requires intense focus, lightning-quick reflexes, and stellar hand-eye coordination, he said.
On the contrary, all they need is patience, Dobleman tells them -- they'll develop these other skills over time as long as they practice.
"Anybody who can walk and chew gum at the same time can learn to juggle," he said, adding that he can teach anyone older than 11 in 20 minutes.
He drove his point home by showing new club members the skills of students who joined just a few weeks earlier.
Joevon Hatter-Oyedeji assured the skeptical that his geometry teacher isn't exaggerating.
"You can learn scarves in 15 minutes," said the 10th-grader, who graduated to juggling rings a couple of weeks ago.
He joined the club figuring that the better his hand-eye coordination gets, the better he will be able to dribble a basketball when he joins a league next month.
The 15-year-old has seen a difference already.
"I've noticed that my ball handling is a lot better than it used to be," Hatter-Oyedeji said.
Instruction starts with a single gauzy, neon-colored scarf, which students throw and catch over and over to hone their reflexes.
By adding a second scarf and then a third to the routine, their sense of timing also begins to improve as they toss each into the air with one hand and catch it with the other.
From there they progress to lacrosse balls, large plastic rings and finally foam clubs while learning additional patterns such as Siamese clubs and the caterpillar.
Andy Clausen, 14, has taken the circus art one step further, having adopted a contraption known as a "diabolo" as his toy of choice about six weeks ago.
The prop consists of a spool in the shape of a large hourglass and a string attached to two sticks.
The idea is to manipulate the sticks -- one in each hand -- to get the spool spinning on its axle along the string and then flip it into the air, using the string to catch it on the way down.
"I got really addicted," Clausen said as he deftly whips the oversize yo-yo down the length of the string and back again to accelerate its spinning.
"It uses a lot more physical movement -- with this I use my whole body."
This test of aim and manual dexterity might help his performance on the school's tennis team in the spring, Clausen said.
He also cited a benefit that's sure to make Dobleman the envy of his peers.
"I pay better attention in class now," he said. "You can take distractions and just ignore them."
Reach Rowena Coetsee at 925-779-7141 or firstname.lastname@example.org.