Sunday, November 30, 2014

The History of Everything In 45 Minutes

Elementary lectures are tricky.

You're not really supposed to do that if you're an elementary teacher. Give 'em a quick mini-lesson and send them on their way to do something a bit more productive than sitting.

Unless you have a bunch of scribbling behind you. 

But once in a while a good chunk of lecturing can make kids more curious, more excited, and more ready to learn. If you have the right kind of student, a "6 Levels of Moral Development" lecture can be pretty enlightening. Personal connection stories can also be successful. So if I'm teaching personal narratives, I often share stories like this one, or this one, or this one, minus the beverage review.
Last year fifth grade was learning about Malaria, and I can ramble about that one too.

But with all of those I can bring personal experience into it, which makes it infinitely more interesting to my target age group.

You're not my target age group

Today I tried something a little different. We're starting a new unit in 4th grade on Technology and Innovation. I asked the kids to write down what they thought technology was. Here are all their responses squished into one:

"Technology are things that need electricity, for example computer, iPad, iPhone."

This is probably has something to do with how we use the term in everyday life, and a lot to do with us just finishing a unit on electricity.
I decided in order to tell the story about technology, I'd have to go back to the development of us and our migration. And to tell that story, I might as well talk about the distinction of the dinosaurs so that people could have room to evolve. And what the heck, let's just start at the Big Bang. I decided to consolidate some of my favorite resources and condense them. 
Here we go:

Since we've been studying number lines, I wanted to demonstrate a timeline of the universe up until now. Chronozoom has a decent one. But I wanted to show our history more tangible than a quick zoom, and less tangibly than using toilet paper. It turns out that this Crash Course in Big History #1 squeezes all history into 13 years:

Quick Notes:
- If everything that we know can be compacted into 13 years, then 13 years ago our universe was born from the Big Bang.
- The first stars and galaxies were born about 12 years ago.
- Earth formed about 4.5 years ago.
- 4 years ago, the first single-celled life formed.
- 6 months ago, multi-celled organisms sprung to life.
- The dinosaurs went extinct 3 weeks ago.
- Humans and chimpanzees split from their last shared ancestor 3 days ago.
- The first homo sapiens appeared about 50 minutes ago.
- We left Africa 26 minutes ago.
- We invented agriculture 5 minutes ago.
- Ancient Egypt was 3 minutes ago, the Black Death was about 24 seconds ago, and World War I was 2 seconds ago. 

The Big Bang and the Formation of the Universe:
Here's David Christian on the TED stage roughly talking about the same thing. By the way, did you know that the moon was formed because the Earth collided with something about the size of Mars? That's in a later video but that tidbit fits better here.

Quick Notes:
- Everything came into existence with the Big Bang, about 13.7 billion years ago.
- The universe is tiny, smaller than an atom, incredibly hot, and expanding.
- 380,000 years later (twice as long as humans have been around) atoms were born. 
- Stars started igniting into existence about a 200 million years later. 
- When large stars die, they create the elements that are found on the periodic table- the ingredients that were necessary for our solar system to be born, 4.5 billion years ago.
- The goldilocks conditions for life are: the right amount of energy, diverse chemical elements, and liquids. Planets are great for these conditions. 
- 6oo million years ago, multi-celled organisms appeared.
- 65 million years ago, the dinosaurs were wiped out by an asteroid- great news for a mammalian ancestors. That event gave mammals the breathing room to evolve. 

Earth, not to mention the life that's contained on it, is a relatively new phenomenon. And it's constantly changing. 
I can throw in a gif of plate tectonics to illustrate that:

But I care more about how life has changed in this lecture on this History of Everything in 45 minutes, so I have to choose my battles. Sometime before the dinosaurs, in the Paleozoic period, giant insects were everywhere. Why aren't there giant insects any more? The prevailing theory is that they were conducive to an oxygen-rich atmosphere. With that oxygen started to dissipate, insects couldn't grow to their massive size anymore.

And then the dinosaurs. Did you know that the amount of time horned dinosaurs were around is longer than the amount of time since their distinction? Speaking of distinctions, this explanation from Radiolab is almost as amazing as it gets:

Quick Notes:
- Sometime between June and July 65 million years ago, a meteor the size of Mt. Everest hit southeastern Mexico at about 20,000 mph. 
- If the dinosaurs had the right kind of eyeballs (they didn't) and they were watching this asteroid fall, they would have seen an atmospheric hole rip through the daytime air, revealing the stars behind it.
- The asteroid hit the earth with an explosion of a hundred million megatons. To put that in perspective, 2 tons of TNT will bring down a building. 15,000 tons of TNT was dropped on Hiroshima, a current Hydrogen bomb is a million tons of TNT (1 megaton). To destroy the entire planet, you'd need 110 quadrillion megatons (100 million times 110 million) of TNT.
- The sun's temperature is about 5000 degrees. The point of impact would have been about 20,000 degrees- 4 times hotter than the sun. 
- The asteroid ploughed 20 miles into the earth, and because of the temperature, it turned all of that rock it touched into a gas. 
- That gas-rock shot into the atmosphere. Some of it escaped to the moon and beyond, but about 90% of it was held onto by Earth's gravity, spreading around the Earth. The gas cooled, and condensed it into little droplets of glass the size of sand. 
- There are now trillions of droplets of glass falling around and in the earth's atmosphere, burning up and creating the most magnificent meteor shower ever.
- For each droplet of glass burning up, it's depositing a little bit of heat into the air. Since there are trillions of these things burning up, the heat deposited in the atmosphere is growing and growing, turning the sky red. 
- The temperature in the atmosphere grew to the temperature of a pizza oven (1200 degrees). At this temperature, no matter what kind of skin or scales you had, your blood would start to boil. All dinosaurs everywhere died within two hours of the impact. What would have been more amazing is if the trillions of pieces of glass fell from the earth atmosphere and shredded up everything.

- Ocean creatures within 300 feet of the surface would have also died. Anything below that could have survived.
- Dirt makes a good insulator. You only need a few inches of dirt for protection. Any animals in the ground would have survived. Somewhere in a little hole in the ground on that day was a furry animal that was your great great great great (times a lot) grandma.

The dinosaur extinction gave way for mammals to evolve, until evolution spit out us in Africa. 

- We are an upright, walking, big-brain, intelligent ape. We are one species of about 5500 mammalian species on the planet now.
- We are one species of at least 16 upright walking apes that have existed over the past 6 to 8 million years. Neanderthals existed for about 500,000 years before us, and early Homo Sapiens actually lay with them. However, we are the only upright walking ape that exists today.
- We've only been around for about 200,000 years. Technology has removed the checks and balances of our population growth. We're the only animal that makes conscience choices that are bad for our survival as our species. 

In the past 150,000 years, here's one theory on how we spread:


- 200,000 years ago we were all dark skinned in Africa. Melanin, the skin pigment, protected us from the sun. How we adopted and changed our skin color in such a short amount of time is still a mystery.
- We all share a single ancestor, Mitochondria Eve, who lived 200,000 years ago and who is the mother of all of us today.
- What's even more amazing is that Mitochondria Adam lived about 60,000 years ago. Which means that all of our diversity is only 60,000 years old.
- We started to leave Africa around 60,000 years ago, because of the weather. It was the worst part of the last ice age. Africa wasn't covered in ice, but it was drying out. Ice sucks moisture out of the atmosphere, and the Sahara was much bigger then.
- The human population around then was around 2,000. We were nearly extinct. And we are highly inbred because of this low population such a relatively short time ago.
- Mt. Toba didn't make anything better. The largest volcanic eruption over the last 20 million years in Sumatra created a global nuclear winter.
- Language and becoming more social as a species allowed us to survive.

On our incremental migratory journey, farming and boats let us spread out further. And now I'm at the point in our story where I have planted a few seeds of what else technology could be. In the coming days we'll make a list of some possible technologies, group them, take a field trip to The National Technical Museum in Prague, and refine our definition. Eventually we'll get to a working definition used by this guy:

But that's another story.

Monday, November 3, 2014

Understanding Current Electricity With Conductive Dough

I've noticed something about myself. Between August and October, I don't write much here.

I blame school.

If I had a regular reader of this blog, I would apologize profusely. But since this space likes to pretend it's part of the deep web, even though it isn't, I'm not sorry at all.

I blame this blog.

You hear that blog? I'm not impressed with your superpower choice.

When choosing between the superpowers of invisibility or the power of flight, this blog has chosen invisibility

Onto the program!
After practicing extensively with batteries, lights, wires, and circuits in general, last week my kids made a batch of conductive dough. Why? Well, making food-like products is a great math unit in measurement. Also the dough replaces wires in a traditional circuit, and it's a challenge to extrapolate what the kids learned with current electricity and wires and apply it to another substance. 
How do you make conductive dough? From the squishy circuits website, mix together:
1 cup of water,
1 and a half cups of flour,
1/4 cup of salt,
3 Tablespoons of Cream of Tartar or 9 Tablespoons of Lemon Juice,
1 Tablespoon of Vegetable Oil,
And maybe some food coloring

I gave all the groups a tablespoon, and asked them to choose and rationalize their second measuring tool; either a cup, a 1/2 cup, or a 1/4 cup.
Most groups chose the 1/4 cup. Yay!
For an extra challenge, I asked a couple groups to make two servings in one batch.

I'm dealing with a small sample size, but it seems like every year two things will happen:
1) One group will totally not follow the recipe, and
2) Another group will spill their contents on our carpeted floor. 

Both problems are salvageable. The former can be corrected by adding extra water and burning it off while it bakes, and the latter problem can be remedied by scooping it back in the bowl. 
The end result... before it was cooked, and after it was scooped back in the bowl

But before we try to figure out how conductive dough works, I give them this photo problem:
In the picture, all components are working. The batteries, bulb, wires, and holders all work great. But the light isn't on. Given what you know about electricity and how it flows in a circuit, why doesn't this circuit work?
The crossed wires might be confusing, but that's a red herring

I don't really expect many to figure out what's wrong even with an extensive knowledge of the tools here and a passing knowledge of current electricity.
The reason is because of that red bulb holder. The two pieces of metal are touching, and electricity will always follow the path of least resistance. It's much easier for current electricity to go through a conductor such as metal than a resistor like the bulb. So it takes the easy path. The bulb has no current passing through it to light and heat the filament inside. 

It's a point I'd like the children to internalize. To check if they do, next I give them a glob of conductive dough, a battery pack, and an LED. I ask them to think about this picture, the problem, and the solution, and to extrapolate that knowledge to make a squishy circuit.

They planned it out, made a diagram, drew the path of electricity to the squishy circuit, and most came up with is some variation of this:
"Ryan, I think the bulb is broken"

So I brought them back to the first photo, emphasizing the path of electricity. Then asked them reconsider their squishy circuit. Most then were able to see the problem in a different way, and their trial and error had a lot more purpose. Eventually they reached a conclusion: You have to force the current into the bulb, and sticking it into the conductive dough just won't work.
What does work? This:
I love this lesson. I love not only playing with other materials out of the students' comfort zone, but extrapolating lessons from one set of materials and applying it to another set. If only there was some sort of non-messy liquid conductor that could pose the same kind of challenge through extrapolation...
oh, wait.

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