World 4-2 (New Super Mario Bros.)
From the Super Mario Wiki
World 4-2 is the second level of World 4.
This level has purple Mushroom Platforms that tilt accordingly to Mario's weight. The first Star Coin can be obtained by Wall Jumping to it. To get the second Star Coin, Mario must let one of the purple mushrooms tilt to the right. Once the player gets it, they should jump off onto the next mushroom. Soon after the Star Coin is a Red Ring. Mario will come to a stepped platform. If he jumps on the purple mushroom after it, lets it lean to the left, and then jumps to the Brick Block and hit it, he can reveal a Beanstalk leading to a bonus area. The third Star Coin is present there. Then, he should enter the Warp Pipe and touch the flagpole, ending the level.