How to open world 4 and world 7 on new super mario bros on nintendo ds?

Question

Can anyone tell me how to unlock world 4 and world 7 on this game.

i have completed worlds 1, 2, 3, 5, 6, and 8 (ive defeated bowser in the big castle at the end of world 8) but worlds 4 and 7 are still locked.

Help!! Thanks.

Answer 1

You need to beat the boss at then end of world 2 and world 5 as mini mario.    

Answer 2

Yeah, beat the Bosses as Mini Mario/Luigi.

(have a blue shell)

It's really hard. =D

Answer 3

Yeah, i wondered about that too. But i figured it out because im so smart. =D

World 4: Okay, go to world 2, and the very last level, the castle. Go through the blue part, but when you get to the desert part, at the end, there is a mystery box that has a mini mushroom. Get it. Then, dont go get a mushroom to be regular stay mini, and go to the boss. You have to defeat the boss level while being mini, and then it will take you to level 4.

Level 7: Same thing. All you have to do is beat the boss while being mini. Simple.

Good Luck!