Madonna: From Material Girl to Proud Mom

Madonna's biggest fan is pretty close to home — it's her four-year-old son David, who knows all the lyrics to her chart-topping hits. 

"He knows every song, every word, every step, and he wants to wear all the costumes. He likes my dress that I wear in 'La Isla Bonita,'" the 51-year-old revealed on the UK's GMTV show.

Madonna says that her children are taking an ever increasing interest in performing: Rocco (her son from her marriage to Guy Ritchie) and her daughter Lourdes, have been taking private lessons from her backing dancers, without their mom's knowledge.

She said she was ''surprised'' that nine-year-old Rocco, took to the stage during her Sticky and Sweet world tour, adding that he has "come out of his shell".

''When he jumped on stage to dance in my last show I was shocked actually and secretly, unbeknownst to me, they're all studying privately with my dancers," she said.

''Rocco comes out and busts out like a moon walk or you know, some kind of break dancing move and I'll ask him, 'Where did you get that?' He's always been quite shy so I was shocked when he wanted to be in the show.''

Lourdes, 13, appeared in Madonna's video for "Celebration" by dressing in her mother's iconic '80s outfits and performing a back flip.

"She's been doing rhythmic gymnastics for years, she's very flexible, she's a great dancer, it was one of those fluke things," the singer says, "we didn't intend for her to be in the video, we did intend for to be in the part where she dresses up in one of my costumes.

"But the part when she's dancing with my dancers — she's very friendly with my dancers — and they kind of dragged her into it. And, it was a small little piece... It was great. She's a showgirl."

Madonna, who is also mother to Mercy, 4,  said of Lourdes' appearance on stage on tour, ''I really thought of her in a very professional way, and I didn't want to distract her.

''I checked her out a few times in the show and she looked so chilled out and laid back and nonplussed by the whole thing, that I was like, 'OK. I'm not worried about her!'''

So, what do the children think about life with their mega-famous mother?

"They get great bonuses and perks out of being my children and they know it, and they're very grateful and appreciative for it," she said.

"I think they are pretty balanced in terms of how they view fame or celebrity or things like that. I think it took them a while to adjust, but I think they're okay about it."