This is very much an up-in-the-air level, with the focus here being on platforms with springs to get you up and flying. This level also introduces a new enemy – flying turtles – which also kind of introduces another technique which is useful for later levels, in that killing flying enemies requires a jump onto the head, rather than a jump into them, which really just kills you (or shrinks you, or knocks you back a few paces in your ‘try again’ bubble).
The other thing that this appears to introduce is the ‘red rings’, which brings with it a challenge to collect five red coins. At least I think it’s five, I couldn’t find any others, and by the time I got them all the timer had run down anyway. I’m not sure what this gets you, but I’ll endeavour to learn throughout the rest of these levels.