Nicole Richie thinks it is "fun" to take her kids on tour with Joel Madden.

She said: "It's fun. It's a very cool experience, especially for the kids."

Being on the road as a family has allowed them all to spend quality time together, discovering new places and having different experiences.

Nicole said: "I'm always finding the fun places in each city, and I probably wouldn't do that if I didn't have kids.

"I think they just like sleeping on a bus and waking up in a different city every day.

They get to hang out with us all the time. They've probably been in every mall all over America by now. We went to the Mall of America, which is in Minneapolis. It is massive. And there is an amusement park inside, cute little rides, and a roller coaster."

And Sparrow is already showing signs in following in his 37-year-old dad's rocker footsteps.

Nicole said: "My son likes to dress like his dad."

However, Harlow isn't always as keen and sometimes misses the group's gigs in favour of "hanging out" on the tour bus.

Nicole added to People magazine: "And sometimes my daughter doesn't even come. She's a little more reserved. She'll hang out on the bus and do art. The bus is awesome."

A few weeks ago, the 34-year-old star praised her spouse - who she married in 2010 - for being a great father and admitted she hopes Sparrow grows up to be just like him.

She wrote on Instagram: "Thank you for making me a mommy...Thank you for encouraging our children to be human instead of perfect. And thank you for your unconditional love, patience, & acceptance. I hope our son turns out to be just like you. #happyfathersday @joelmadden."