Sessions usually start with a brief introduction and discussion about what each child might like to paint.

"We let them do what they want," says gallery director Cherry Ho Tsz-ling.

"We offer some guidance if needed. Mainly, we encourage them to draw ," she says.

This is a highly attractive - sometimes the most challenging - aspect of using the wall as the canvas.

Jovie's mother, Phoebe Ma Wing-yee, says: "It's a bit strange drawing on the wall, but they seem to like it because they can't do that at home."

Henry Chan Shum-ning, who was there helping his six-year-old daughter, says: "It's the first time she's drawn on such a big canvas. It's different from other kinds of painting as there's no frame."

Fiona Chan Siu-yu, 13, says: "It's quite fun." She is helping her little sister with a painting of Olaf, the snowman character from Disney's hit cartoon, . "I like to draw quite a bit, but I haven't attended an art class since kindergarten."

The concept of art jamming began with Betty Cheung Yee-wan, whose company, Art Jam, provides a "motivation painting experience" at its premises in Central, in pursuit of creativity, productivity, self-discovery and balancing the mind.

Initially catering to adults, Art Jam began to include children in 2001. "After a year or two, we introduced smaller canvases, which the parents felt were better for the kids, though the kids were fine with any size," Cheung says.

"The majority of the families that come here are interested in the childrenbeing creative and more confident."

She recalls a mother who brought in her hyperactive nine-year-old son and an extremely shy daughter who took two hours to even try to paint. "But when she finally did ... she couldn't keep quiet. She kept asking if they would be coming back next week. Her brother, who apparently can't sit still at home for 10 minutes, focused for 3½ hours. Their mother was amazed to see them each hit their own little milestones."

Anissa Fung Siu-han, associate professor at the Hong Kong Institute of Education, says the gallery setting makes a difference because "children can have a direct encounter with the artworks displayed onsite". Galleries can also help to foster art literacy in the young so that they will become educated audiences and consumers of art, she says.

Cheung says: "A lot of art classes limit kids as they have to repeat what someone else has shown them. One of the first things a parent might want to do is draw for the child ahead of time."

It's easier to get younger children to be "creatively crazy", but older ones often have to be coaxed like stubborn adults, she adds.

"For us, it makes no difference if it's a four-year-old child or a 49-year-old child. It just matters that they're willing to try it. Kids' confidence and ability to tell stories come from them having a healthy imagination. They've got to exercise that."

Unlike regular art classes, these events are often family affairs. At Artify, Ho points at a rendering of the Studio Ghibli character, Totoro. "The whole family was involved - the mother drew, the child painted while the father took photos."

Artify's staff usually whitewash the walls after each session so they present a blank canvas for the next set of children, but the murals can be photographed and printed onto canvases, or as phone covers, to take home.

Ho believes parents enjoy the gallery setting, but opening its doors to children means changing the vibe of the space - at least while they're there. Artify looks like a typical gallery, but staff are laid-back about children running around during wall painting sessions.

168 Gallery, in Sai Wan, was one of the first galleries to open its doors to children. Its larger space enables it to offer diversified services in addition to its exhibition schedule - from art classes, that include painting and ceramics, to art parties for children, to freestyle painting sessions and framing.

"People find it quite attractive to learn to draw in a gallery," says owner Fanny Tang Bok-yin. "They get inspired by the exhibitions we have running."

168 Gallery has separate areas for exhibitions, a studio space with canvases, art supplies and books, and a kiln for ceramics classes. The children are encouraged to explore exhibitions, but are schooled first on etiquette, such as learning not to touch the artworks.

"We start with a brief introduction on colour and how to sketch," says Tang. "The older kids usually work on their own, though it helps to have a theme. Sometimes, a group can come together to work on one painting."

The sessions differ from regular classes, Tang says, because the youngsters are free to paint what they want and do not have to commit to a schedule of classes.

The gallery hosts about 10 such events a month.

Tang, who is an artist herself, finds the sessions inspiring. "Spending time with kids does give me new ideas for my own painting," she says. "Their imagination is wild."

Artify has also involved a couple of the artists that it represents. "They enjoy interacting with them, and get inspired by them," Ho says.

"For example, one of our artists brought different materials, such as balls and string, and urged the children to use them."

The gallery has been encouraged by the response to its first offering for children and plans to do more. "Normally, we do exhibitions," Ho says. "This is a very different kind of activity. I think we'll do it regularly over the summer."