By this time they've taken their graduation tassels and yearbooks and put them away in a box with all the other mementos of high school.
For many newly minted graduates, summer is the time to make travel plans. They have airplane tickets to buy, or long drives in August and September to think about. They will journey over the Tejon Pass, or across the Mojave Desert, to the college towns and dorm rooms that await them.
But before you leave us, class of 2009, before you go on that first big adventure of your adult lives, do what Luis Penate is doing in the last few weeks before he leaves South Los Angeles for Swarthmore College in Pennsylvania.
"I want to go around and see some L.A. landmarks," he told me. His plans include one last look at the downtown skyline before he says goodbye.
Luis says he'll wander around a bit so L.A. stays in his memory, because he's already been to the East Coast once (on a college tour) and knows how different it is from our dry city by the sea.
I'm very glad Luis doesn't want to forget us. Because Luis is a thinker and a fighter, an 18-year-old Angeleno who wants to change the world. He's already done one courageous thing in his young life -- it was last year, about the same time Californians were going to vote on a controversial ballot measure.
We need Luis and all the other college-bound members of the class of 2009 to come back to Los Angeles one day. We need their brain power to sort out the messes we older generations are leaving them.
Luis is one of those young people who was gifted to us by El Salvador, a little Central American republic that has lost too many of its brightest and most ambitious people to the United States.
His mother, a legal U.S. resident, had spent much of her life traveling back and forth between the two countries. When she brought Luis to the United States, at age 11, he was already a precocious reader. He had just read "The Lord of the Rings" in Spanish.
He spoke no English, however. But he learned quickly, and in the sixth grade his English reading abilities took off. In the span of a few months he went from reading "Clifford the Big Red Dog" picture books to Harry Potter.
"One day I woke up and I realized, 'I know how to speak English,' " he told me.
Luis, who became a U.S. citizen last summer, also had the good fortune to be one of the first students in the Los Angeles Leadership Academy. The academy is a charter school that opened in 2002 in the Koreatown neighborhood where his family lived at the time.
The school was founded by a New Jersey-born lawyer and screenwriter named Roger Lowenstein. It was Lowenstein who introduced me to Luis, telling me he was a natural writer. Several colleges, including UC Berkeley, Vassar and Amherst, sent Luis acceptance letters.
"I love language," Luis told me. "I've always wanted to be a writer, and to have a voice and to speak out."
At the Los Angeles Leadership Academy, he tried his hand at op-eds for the school newspaper. He wanted to provoke his fellow students. Last month, he wrote an article decrying the lack of ambition among many students at the school.
"They fuss with make-up when a teacher is trying to show them how to find the derivative of a function, or crack jokes while we watch videos of the Holocaust," he wrote.
The response: silence and apathy. He wondered if they'd even read it.
He had more of an impact with an essay describing how he told his friends and classmates he was gay. It has since been republished on the website RadicalParenting.com.
"It was coming out or suicide," he wrote. "I couldn't go on living with who I was pretending to be; it's like living with your worst enemy, except you share one body."
Last year, Luis worked for the No on 8 campaign, which sought to defeat the voter initiative outlawing gay marriage. He circulated pamphlets and went to marches, but at home he kept quiet, because his parents still did not know he was gay.
Both were opposed to gay marriage. His mother had become a U.S. citizen and was saying she would vote for the ban. Luis was afraid to say anything, until one night, while making dinner in the kitchen, it became too much to bear.
"I cried for 10 minutes, trying to decide whether to risk the love of my parents for one vote," he wrote. Finally, he told his mother his secret. She wept, embraced him and then announced, "We need to tell your dad."
Luis describes what happened after he told his father, "I'm gay." "The words escaped from my mouth and filled the stale air." His father kept silent and then "signaled me to sit on the floor next to him. I did as I was told. He hugged me tightly with both arms and said: 'I don't care. You are my child and I will always love you, no matter what.' "
His mother ended up voting no on Prop. 8. And when I visited Sonia Moran and Rogelio Penate in their South L.A. living room, both nodded when I asked if their son had changed their views on gay marriage.
"You see something different when it touches your family," Moran said. "Our son was brave. It hurts me to know he suffered so much without telling us."
Later this summer, Luis and his parents will travel together to Pennsylvania. And then Sonia and Rogelio will say goodbye to their son, as will many other Southern California parents.
The graduates of the class of 2009 will study the works of Shakespeare, Darwin, Jefferson and so many other important and wonderful things.
And while they study, I hope they will remember this: We're all back here in L.A., rooting for you. Don't forget us.
Come back one day to this city that needs you, to this city that once held your secrets. Come back with your knowledge and vision, to this city where barriers fall and where there are people waiting to tell you unexpected things like, "I will always love you."