Yes, yes it does. Thanks. The end. Bye!
LOL. JK. But seriously: Volume is a capital-R Real characteristic of all forms of matter. But not all matter’s volume is created equal. By which I mean, different materials will occupy volume differently, depending on their structure. To wit: does a cup of sugar occupy its volume in the same way a cup of water does? They’re equal measurements, but their volumes couldn’t be more different*
This easy peasy lemon squeezy Demo Science experiment will help you explain this concept to your students. Take a gander, salamander!
This Experiment Goes to 11
For this bad boy, you’ll need a glass jar, three cups of water (divided—i.e., three individual eight ounce “servings” of water), one cup of sugar (also eight ounces, if you’re not up on your conversions), tape (preferably masking), and a writing utensil.
Rip yourself off a strip o’ tape and affix it vertically to the outside of your jar. Next, pour in your first cup o’ water and mark the level of volume occupied by said water on the tape with a “1”. (It doesn’t need to be super perfectly perfect, but if one of your students, perhaps by the name of Kevin, is gonna be a stickler about it, you can go way over the top and get a capacitive level sensor to give you the most ridiculously and unnecessarily exact reading possible—that’ll shut him up.) Then, pour in a second cup of water, and mark its level on the tape with a “2”.
Pour out the water, dry out the jar, and pour in your sugar. If everything is in of whack, the one cup o’ sugar should reach the “1” mark. Before you continue, ask your students what they think will happen when you add a cup of water. Will it reach the “2”? Have the smelly little buggers write down their hypotheses.
Add the third cup o’ water, and give the whole thing a stir. If all goes as it should, you’ll find that the total level in the jar is now well below the two-cup mark. But how? The “2” was two cups, and you just added two cups. What happened, students?
2 Cups ≠ 2 Cups
The culprit here is the differing structures of the water and sugar. Though sugar granules themselves are solid, taken together in, say, a one cup measurement, they don’t create a truly solid solid. There are countless spaces—miniscule air pockets, really—betwixt the particles.
Water says, “Hey, nice air pockets ya got here, pal. I’ll take the lot of ‘em,” and fills in those spaces. As the water fills these tiny voids, it pushes the air out of the way, which is why you likely saw some air bubbles plorping up prior to stirring the mixture. Because it eliminates the spaces between the sugar granules, the water effectively “shrinks” the volume of the sugar.
* Actually, they could. But that’s a tale for another time…