World 1-2 (Super Mario Maker for Nintendo 3DS)
From the Super Mario Wiki, the Mario encyclopedia
At the level's start, there are four stacks of red and green Koopa Troopas, all with a big Koopa Troopa on the bottom. Kicking the big shell in the second or third stacks can break the Hard Blocks and open up the space underneath two ? Blocks, one of which contains a Super Mushroom. Similarly, Mario can use a big shell to plow through the Brick Blocks in the subarea, accessible via the Warp Pipe marked with an Arrow Sign. On the other side of the wall, Mario can kick the Koopa shell to the right to grow a Vine to the section above, or use Lakitu's Cloud to fly up instead. On this Cloud Block platform, there are two Hidden Blocks; one with a green Koopa Troopa, and one with a Weird Mushroom. Through the Warp Door comes one last Koopa Troopa stack, this time with a jumping Koopa Paratroopa on the bottom, followed just after by the Goal Pole. The three Coins in the air are markers for Hidden Blocks, which the player can use to reach the top of the Goal Pole if they wish.
Alternately, Mario can forego the Warp Pipe by revealing Hidden Blocks marked with Coins to go over the tall wall at the right; this is required for the Goomba medal (see below). If the player does choose to use the Warp Pipes, they can use Lakitu's Cloud on the other side to fly through the Cloud Blocks and sneak underneath the Warp Doors for the Bowser medal.