I recommend doing that on a tutorial world. When you start the tutorial world, hit B when the text box at the top right corner wants to teach you how to play Minecraft. Don't hit A, or you can't cross the bridge until you finish the basic tutorial! You need to cross that bridge, and behind that big diamond pickaxe and these stone stairs you shoud see slime blocks on the Dried Kelp blocks. Sprint by hitting
two times rappidly and try to land on water or slime blocks. Don't fall on any other blocks or you will end up receiving fall damage! Now, after you successfully landed, mine the Kelp Blocks that are beneath the slime blocks. Then go back to the bridge (you may find the stairs leading you to the bridge). This step is self explanatory. Try mining 8 cobblestones by gaining wood and then crafting a pickaxe. Go back and start crafting a Furnace. Place the furnace and place your Kelp Block(s) to Fuel. You will instantly earn the achievement.