I like to use urban myths to introduce this concept. After all, what's more fun than pretending to be the Mythbusters? One of the best myths from my childhood was the Pop Rocks and Coke belief.
I find it funny how few students even know of it now, so I show them a couple of videos to get their minds working in that direction.
This one is my favorite. I let them wonder about what happened and why. We record our observations and hypotheses on the sheet below, created by another teacher (Time2Teach). Here's the link to her Teacher's Notebook.
I really like this foldable because it's simple and there's plenty of room to write student observations in the middle. Of course, I let them taste the Pop Rocks before adding the Coke and amend their hypothesis if need be. Then the magic begins!
We also discuss variables and how the Coke is the variable in this experiment because it's the only thing that really gets added or changes. A great website to let the kids practice variables is Blasto! It's about a human cannonball. It lets them adjust variables such as angle of the cannon and gun powder. It's great for discussing not changing too many things (variables) at once!
Do you use the Scientific Method? I'd love to hear your ideas on lessons, websites, foldables, and videos!