[blank_start]To begin with,[blank_end] make sure you are doing this experiment in a place where you won't get in trouble for getting Diet Coke everywhere. Outside at the yard is perfect, please don't try this one in your living room!!
Then, [blank_start]place[blank_end] the Diet Coke upright and open the bottle.
[blank_start]After that[blank_end], put a [blank_start]funnel[blank_end] or tube on top of it so you can drop the Mentos in at the same time.
[blank_start]Once[blank_end] you put the tube, it is time for the fun part, [blank_start]drop[blank_end] the Mentos into the Diet Coke....
[blank_start]Lastly,[blank_end] run like mad! A huge geyser of Diet Coke should come flying out of the bottle, it's really impressive!