(LEGO) Block Party: Crash Course Kids #23.2


[INTRO MUSIC] Oh, hi there! Yeah, you caught me. There’s nothing that says big
kids can’t play with LEGO too, but you know, these LEGOs are business-related. Being the sciency type, I can use
them to learn about things, like… mass! Like, if I measure the mass
of all these LEGOs separately, and then compared them to the
mass of the building, or the dinosaur, or whatever I make when I put them together, then I find that the masses are always the same. But you already knew that, because you
remember all about the conservation of mass, the rule that says mass is never made or lost. We tested that rule out by making matter go through
physical changes, like mixing it into a solution. But what about chemical changes, like those things
that happened during our cake-baking adventure? Does conservation of Mass apply there? You know that during chemical changes, the particles that make up two or more substances
become rearranged to make a new substance, and then there are things that give us
clues that a chemical change is occurring, like a change in temperature, or lots of
bubbling, or maybe even a flash of light. You also know the special names that scientists give
the substances that take part in a chemical reaction: the reactants are the substances that you start out with – that’s the stuff that’s made of the particles
that get rearranged during the chemical reaction. And the new substance that gets made?
That is the product. And I bet we can show what happens during
a chemical change by using my LEGOs. See? And you would have an excuse to play with these! if we pull the cubes apart, mix up the LEGOs and build something funky-shaped from the
exact same blocks that made up the cubes… That’s our product. Well, I did say funky-shaped! Notice that it’s made of the same
LEGOs as the original cubes, they’ve just been… rearranged. It makes sense that the mass of this new product would
have the same mass as the original reactants, right? Because they’re made out of the exact same stuff! Ready to test that out? Okay, let’s get experimenting! But instead of playing with LEGOs this
time, let’s mix two liquid reactants, substances that sound terrible
together: vinegar and cream! We’ll measure the mass of each
liquid and record those in a table. Next, we’ll stir them in the same bowl. Gross? Maybe. A good example of the conservation of mass?
Definitely. The two reactants mixed
together made a new substance. That disgusting goop is curds, a solid product
that can’t be turned back into two liquids. So, boom! That’s a chemical change! And the solid product that it formed has the
same mass as the two liquid reactants, which we will now note in our trusty table. Now, the mass would still be conserved, even if the chemical reaction makes products that aren’t solid. Like, if we were to mix a little bit
of vinegar with baking powder, it would make a lot of bubbly foam,
which is caused by a release of gas. And gas, if you remember way back
to our balancing balloons experiment, is matter, and has mass. No matter what state the products are in, if you add up the mass of all of the products, it
will always equal the mass of all of the reactants. So, the mass is always conserved,
or saved. It never goes away. And as we saw in our vinegar and cream experiment, chemical changes — like physical changes —
follow the conservation of mass, that scientific rule that says matter
can’t be made, and can’t just disappear. Okay, now that the business part is
over, I’mma build me a velociraptor. It’ll be fine(!) [OUTRO MUSIC] Be sure to subscribe for more from Crash Course Kids!

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Reader Comments

  1. YoungTheFish

    Crash Course Kids! Proving that kids these days are smarter than many adults.
    I'm glad I still remember most of the things you are teaching…

  2. King Kirby

    So if I melt an ice cube, the water will have the same mass as the cube did right? Also, if I evaporate that water into water vapor, will that gas also have the same mass as the water and the ice cube?

  3. Davide Longo

    I LOVE LEGO TOO!!!!! see, we both have something in common. we both like pokemon and lego. but if you like minecraft we would have three things in common. oh wait we do have three things in common. not minecraft but science 🙂

  4. Renee Sojcher

    Great video! Used it with my 7th grade students. But slow down your speaking Sabrina – this info has to sink in and when you talk so fast my weaker students miss the point!

  5. Andrea Wallace

    My students want you to know that Lego cannot be in plural form….you have to add bricks or pieces on to the end in order to make Lego plural…for example Lego bricks or Lego pieces.

  6. Bishop Trimble

    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhah sorry but in the commet section below zane he is in my class

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