Musician Jack Johnson sat cross-legged on a mat with his guitar and patted the space in front of him.

"You guys want to come up here, just like storytime?" he asked, prompting several preschoolers to gather closer to him.

"You guys can call me Uncle Jack," he said with an easy smile. He held out his guitar for the children to touch, then launched into a song about sharing.

For the Grammy-nominated singer and songwriter, singing a surprise mini-concert for about 20 preschoolers — along with their parents and grandparents — is a relatively small gig. After all, he just headlined his fourth annual environmental education benefit Kokua Festival last month, has toured the Mainland, Europe and Japan, and it was recently reported that he will headline the Sydney, Australia, concert of Live Earth, a multicontinent series of shows for environmental awareness.

But yesterday's intimate performance for Tutu and Me traveling preschool participants at Wai'anae District Park's community center was still an important one for the North Shore resident.

"I just remember when I was a kid, anytime someone would come and visit the school how much it meant to me," Johnson said. "And for me, it's pretty heartwarming just to see the kids all dancing and everything. I have a lot of fun doing it."

Johnson and musician David "Kawika" Kahiapo sang at other Tutu and Me sites on the island last week through today as part of a joint effort between the Kokua Hawai'i Foundation — a nonprofit organization Johnson co-founded that supports environmental education in schools — and the Partners in Development Foundation, which runs the Tutu and Me program.

The two groups created a curriculum guide for parents, grandparents and caregivers about educational activities that promote environmental awareness, including projects using recyclable material. Johnson also handed out his "Sing-A-Longs and Lullabies" CD for the film "Curious George."

Johnson — accompanied by musicians Kahiapo and Bruce Spencer and Kahiapo's friend Brad Mayhew — sang a few songs from the CD yesterday, including "The 3 R's," which encourages children to "reduce, reuse, recycle."

His popular "Upside Down" song was a particular hit with the children, many of whom gleefully accompanied him with monkey sounds in the spirit of Curious George.

"Those are good monkey noises," Johnson said.

Sage Iokia was among the children who took pictures with Johnson and got his autograph. The 5-year-old "Curious George" movie fan recognized Johnson from the "Upside Down" video.

"He's the greatest player," he said with a shy smile.

"It was just really a shock and a wonderful blessing to see him (Johnson) here," said Sage's mother, Rachel Iokia. "That just made my son's day."

Johnson's visit also was special for 4-year-old Kai'ona Keali'inohomoku and his mother, Christina. Kai'ona plays the "Sing-A-Longs and Lullabies" CD so much that it became scratched, said Christina Keali'inohomoku, who was thrilled to get a new CD yesterday.

"Something about that music makes them calm," she said. "He'll usually listen to it before he goes to bed."

Kai'ona is conscious of recycling, picking up bottles at the park and beach, and making art from recyclables such as cups and straws, his mother said. He learned about recycling "not only through me, but I'm thinking it's because of the music too, because they listen to it a lot."

Johnson, who has visited local schools on behalf of his Kokua Hawai'i Foundation, said he's trying to help preserve the environment for future generations and inspire children to take care of the Islands.

"It's really rewarding to see — just go in and play a little music one day — what those little seeds can plant and what can happen out of it," he said. "And they are the ones that are really going to make change."

Reach Lynda Arakawa at larakawa@honoluluadvertiser.com.