Hey, heredity groups!
(If you need a refresher, check out http://www.siskiyous.edu/class/bio1/genetics)
http://www.quia.com/quiz/806830.html
http://www.proprofs.com/quiz-school/story.php?title=block-4group-2
http://www.biology.arizona.edu/mendelian_genetics/mendelian_genetics.html
http://www.ksu.edu/biology/pob/genetics/intro.htm
http://www.ksu.edu/biology/pob/genetics/dragons.htm
If you feel like a challenge, try out http://biology.clc.uc.edu/courses/bio105/geneprob.htm and see how far you get.
If you run into difficulty, you can comment here or email me and I'll do my best to help.
Sunday, January 26, 2014
Tuesday, January 21, 2014
Physics is why fun things happen
We've entered the new unit of PHYSICS. If something is happening, physics is involved. If something isn't happening, physics is still involved! Physics lies underneath just about everything in science like a sort of science skeleton, because it deals with matter and we're made of the stuff!
Today, the physical properties of snow mean we've canceled class. (Makeup will be this Saturday or Monday, details in the email I sent.) Luckily, the physical properties of the wires and servers that make up the internet mean I can post something on the blog to make up for it.
So pull your kid over and remind them there's no escape from learning!
Consider this video:
Like most things on the internet, it's a funny cat video. And the humor couldn't happen without physics. Try making a list of everything happening in this video. Which ones do you think were because of physics?
Here's another:
What happened here?
Finally:
Today, the physical properties of snow mean we've canceled class. (Makeup will be this Saturday or Monday, details in the email I sent.) Luckily, the physical properties of the wires and servers that make up the internet mean I can post something on the blog to make up for it.
So pull your kid over and remind them there's no escape from learning!
Consider this video:
Like most things on the internet, it's a funny cat video. And the humor couldn't happen without physics. Try making a list of everything happening in this video. Which ones do you think were because of physics?
Here's another:
What happened here?
Finally:
While this is obviously proof skateboards are deadly, can you see what specifically went wrong? We'll be doing an experiment with washers in next class that will take advantage of this aspect of physics! Also, notice how the boys are falling like pros, minimizing their injury. We'll be talking about (but not practicing!) this next class.
Wednesday, January 15, 2014
Gak! (and Physics)
Gak is a non-Newtonian fluid. In their natural state, glue molecules stick to each other only weakly, which is why glue flows smoothly and why it's easy to smear flat when you're using it to stick two other things together.
Much like the cornstarch used to make oobleck, glue molecules are long and slippery. Unlike oobleck, making gak involves a chemical change and the two ingredients cannot be separated out again.
We made the gak by adding boron atoms (in a water solution) to glue. These atoms crosslink with the sulfur atoms in the glue molecules, causing them to tangle and knot together. This happens immediately, with the glue wrinkling up as soon as boron is added and then forming into ropy webs when it's stirred.
The result is a substance that sticks to itself more than everything else. In fact, gak does so strongly enough that after I made the demo batch, I could clean my hands off by pressing the main ball of gak on my hands so it pulled in the errant bits.
The kids experimented with the gak for a while. Gak bounces like rubber. It rips when pulled quickly but can stretch to amazing lengths if the same is done more slowly. It's also completely non-toxic, so it's safe to eat (although I wouldn't recommend it with how often it fell on the floor). Pressed against interesting textures, it can be pulled off again to show the pattern.
If you do find gak stuck on fabric, vinegar reverses the reaction, breaking the gak back into boron and glue molecules that can be wiped off.
The standard slime gak is more liquid than the version we made. It's fun because it flows more easily but is more of a cleanup concern because it flows more easily into things like cloth and carpet, where it has to be washed out.
If you'd like to try making the slimier version of gak at home, it can be done by mixing equal parts glue and water (most recipies suggest one 8 ounce bottle of glue) and then adding dissolved borax - you can find borax in the laundry aisle as a powder. Add a teaspoon of that powder to a half cup of warm water, stir it up, and add the liquid to the glue. It should turn ropy on contact and tighten up as it's stirred until it's an semi-firm blob, at which point it can be squeezed and pounded into even consistency.
When we finished with the gak and discussing its properies, we moved on to our next unit, physics! We focused g-forces, which produce gravity-like effects. This is what allows people to spin a bucket full of water over their head without any of it falling out. It can also be felt by spinning around with your arms out, being spun around by someone else until you lift off the ground, or spinning in a chair and trying to keep your legs in. While it's mostly fun for fooling around here on Earth, it could be used to simulate gravity and allow humans to live in space indefinitely and even have children born and raised in space safely.
If your kids would like to try it at home, here's a more extensive demonstration video that also gets into Newton's Laws of Motion, which we'll go through in the next class.
Also, here's a video of a bullet fired into a water balloon!
Can your kid figure out what happened? We'll be discussing this and other aspects of physics next class.
Much like the cornstarch used to make oobleck, glue molecules are long and slippery. Unlike oobleck, making gak involves a chemical change and the two ingredients cannot be separated out again.
We made the gak by adding boron atoms (in a water solution) to glue. These atoms crosslink with the sulfur atoms in the glue molecules, causing them to tangle and knot together. This happens immediately, with the glue wrinkling up as soon as boron is added and then forming into ropy webs when it's stirred.
The result is a substance that sticks to itself more than everything else. In fact, gak does so strongly enough that after I made the demo batch, I could clean my hands off by pressing the main ball of gak on my hands so it pulled in the errant bits.
The kids experimented with the gak for a while. Gak bounces like rubber. It rips when pulled quickly but can stretch to amazing lengths if the same is done more slowly. It's also completely non-toxic, so it's safe to eat (although I wouldn't recommend it with how often it fell on the floor). Pressed against interesting textures, it can be pulled off again to show the pattern.
If you do find gak stuck on fabric, vinegar reverses the reaction, breaking the gak back into boron and glue molecules that can be wiped off.
The standard slime gak is more liquid than the version we made. It's fun because it flows more easily but is more of a cleanup concern because it flows more easily into things like cloth and carpet, where it has to be washed out.
If you'd like to try making the slimier version of gak at home, it can be done by mixing equal parts glue and water (most recipies suggest one 8 ounce bottle of glue) and then adding dissolved borax - you can find borax in the laundry aisle as a powder. Add a teaspoon of that powder to a half cup of warm water, stir it up, and add the liquid to the glue. It should turn ropy on contact and tighten up as it's stirred until it's an semi-firm blob, at which point it can be squeezed and pounded into even consistency.
When we finished with the gak and discussing its properies, we moved on to our next unit, physics! We focused g-forces, which produce gravity-like effects. This is what allows people to spin a bucket full of water over their head without any of it falling out. It can also be felt by spinning around with your arms out, being spun around by someone else until you lift off the ground, or spinning in a chair and trying to keep your legs in. While it's mostly fun for fooling around here on Earth, it could be used to simulate gravity and allow humans to live in space indefinitely and even have children born and raised in space safely.
If your kids would like to try it at home, here's a more extensive demonstration video that also gets into Newton's Laws of Motion, which we'll go through in the next class.
Also, here's a video of a bullet fired into a water balloon!
Can your kid figure out what happened? We'll be discussing this and other aspects of physics next class.
Tuesday, January 7, 2014
Atoms, Molecules, Mixtures and Compounds
Hi everyone and welcome back!
Today we started off with a refresher about atoms and molecules. Individual atoms combined into larger molecules can display very different traits. To illustrate this, we made glucose molecules, which are composed of hydrogen, oxygen, and carbon. Despite being made of life-giving oxygen, you can't breathe it, just like you can't breath water despite it containing oxygen. And glucose molecules are the component parts of starches, which taste extremely bland.
Starch is a good source of energy, however, because it can be turned into sugar. In our mouths, we produce enzymes in our saliva that begin to break it apart into those sugars, so that if you hold something starchy in your mouth, it will begin to taste sweeter. It's believed this adaptation helped our ancestors know to eat starchy foods. We tried it out with corn starch and, although it's not very sweet compared to modern day candies we make out of pure sugar, it's still possible to taste the change.
Then we made oobleck by adding water to the cornstarch. Oobleck does not form a new molecule when the two ingredients are combined and can actually be separated very easily - simply squeezing it hard enough, as the kids tried, will push the water out again and turn it into damp corn starch. The resulting substance does have some very unusual properties, though, due to its ability to shift rapidly between solid and liquid depending on pressure. My favorite is that you can cause the fluid to tear if you try to make ripples the way you would in water.
If your kids want more time to play with it, it's very easy to make at home. Just pour some cornstarch into a bowl and add a bit of water until it has the right consistency - your kids should be able to tell you when it's right!
Next week, we'll talk about exactly why oobleck has these properties and then make gak, a compound.
Today we started off with a refresher about atoms and molecules. Individual atoms combined into larger molecules can display very different traits. To illustrate this, we made glucose molecules, which are composed of hydrogen, oxygen, and carbon. Despite being made of life-giving oxygen, you can't breathe it, just like you can't breath water despite it containing oxygen. And glucose molecules are the component parts of starches, which taste extremely bland.
Starch is a good source of energy, however, because it can be turned into sugar. In our mouths, we produce enzymes in our saliva that begin to break it apart into those sugars, so that if you hold something starchy in your mouth, it will begin to taste sweeter. It's believed this adaptation helped our ancestors know to eat starchy foods. We tried it out with corn starch and, although it's not very sweet compared to modern day candies we make out of pure sugar, it's still possible to taste the change.
Then we made oobleck by adding water to the cornstarch. Oobleck does not form a new molecule when the two ingredients are combined and can actually be separated very easily - simply squeezing it hard enough, as the kids tried, will push the water out again and turn it into damp corn starch. The resulting substance does have some very unusual properties, though, due to its ability to shift rapidly between solid and liquid depending on pressure. My favorite is that you can cause the fluid to tear if you try to make ripples the way you would in water.
If your kids want more time to play with it, it's very easy to make at home. Just pour some cornstarch into a bowl and add a bit of water until it has the right consistency - your kids should be able to tell you when it's right!
Next week, we'll talk about exactly why oobleck has these properties and then make gak, a compound.