# November 2010 Archives

## Geometry - Measuring and Constructing Angles

Angles appear often in geometry. Whether you are measuring the angles in a triangle, or determining an angle's type, understanding angles is important. We've got you covered with today's free geometry video on Measuring and Constructing Angles. Professor Burger starts off showing you how to properly name angles based upon two rays and their common endpoint. He then moves into classifying angles. You'll learn about two basic types including the acute angle, an angle that measures greater than 0 and less than 90, and the obtuse angle, which measures greater than 90 and less than 180. If you've never seen a protractor before, you'll learn how to use one to measure angles. The course then moves on to using the Angle Addition Postulate so find the measurement of an angle. And finally, Professor Burger discusses an angle bisector, which is a ray that divides an angle into two congruent angles. Today's video has four lectures on it and you'll want to watch them all. In order to move to the next lecture, make sure you click on the forward button directly to the left of the time stamp.

## Thanksgiving Activities to Keep the Kids Busy

Thanksgiving week is finally here! And I'm sure many of you are running around crazy at the last minute trying to get everything taken care of for the big family feast. Whether you need something to distract the kids while you put the finishing touches on dinner, or you are looking for some fun activities, we've got you covered! After scoping the Internet for fun Thanksgiving activities, we found plenty of things to do with the kids. Here are some of our favorites.

Watch the replay of the Plimoth Plantation Virtual Field Trip webcast. It's a thirty-minute online field trip to meet a Pilgrim and a Wampanoag--straight from Plimoth Plantation. http://www.scholastic.com/scholastic_thanksgiving/webcast.htm

We've all made hand turkeys, but what about a Foot and Hand Turkey? Easy home craft project that can be a nice distraction from the hours of free time.

Want to bring Math into Thanksgiving? Here's a list of activities you can set the kids up to do, including calculating what size turkey you need to feed everyone coming for dinner.
http://www.dreambox.com/blog/thanksgiving-math-activities

I found this interactive game to keep the kids occupied while you're trying to set the table.
This game requires kids to arrange everyone at the dinner table according to their preferences. A nice bit of logic will be needed to succeed at this game. http://www.akidsmath.com/mathgames/thanksdinner.html

This collection of black and white photographs from the Macy's Thanksgiving parade is really great! It highlights some of the wacky parade balloons from the 30s and 40s.

How about pulling the whole family into the activity fun? Set up a Make-Your-Own-Hat station and have everyone make a Thanksgiving hat that they wear to dinner. Visit this site to learn more:
http://familyfun.go.com/thanksgiving/thanksgiving-craft-decorations/thanksgiving-turkey-crafts/make-your-own-hat-station-783848/

Finally, Thanksgiving just isn't Thanksgiving without talking about what we are thankful for. This year, start a Thanksgiving tradition by making a paper turkey and cutting out a variety of paper feathers for his tail. Then, pass around the feathers for everyone to write what they are thankful for on them. Let each person read their feather out to everyone before placing it on the turkey. This is a great Thanksgiving craft for children and really embraces the spirit of the holiday.
http://www.enchantedlearning.com/crafts/thanksgiving/thankfulturkey/

Happy Thanksgiving!

## Geometry - Properties of Parallelograms

I'm very excited to share today's free video because it comes from our brand new online video Geometry course. Folks have been asking us to develop a Geometry course for a while, and with Professor Edward Burger at the helm, you know it's going to be a fun ride! The free Geometry video below covers Properties of Parallelograms. In case you didn't know, a parallelogram is a quadrilateral with two pairs of parallel sides. A parallelogram's opposite sides are congruent, its consecutive angles are supplementary, and its diagonals bisect each other. By knowing these properties, you can easily solve problems that might normally be intimidating. Fear not as Professor Burger will explain everything you need to know to fully understand parallelograms.

Today's video has a total of 4 lectures on it, so make sure you click the forward button to the left of the time stamp in order to view them all!

## Is Our Country Teaching Math the Wrong Way?

I read an article at the end of last week that brought up the point that the US is considerably lacking in what is called "highly accomplished" math students. The scary trend, in my opinion, is how far behind the rest of the world American students are in math.  According to both the article and one of its sources, The HechingerEd blog, the reason our students aren't excelling in math, and in fact falling behind, is because of how we teach math. The examples given for this failure include forcing too much math on kids, not structuring the subject matter in a way where each lesson builds upon the last, and finally not employing teachers who are good at math. Seeing all these negatives made me realize how much American students have stacked against them when it comes to succeeding at math. It also reinforced my appreciation for our math teacher, Edward Burger.  Watch any of his videos on YouTube and you'll quickly see that not only is math his passion, but he also loves teaching math. It's contagious and why many folks love his videos.

You know there are other teachers out there that love math and teaching. Let's encourage these teachers to do their thing and not teach to a test. Instead of focusing on getting students to minimum standards, why don't we focus on teaching them to love math? Why can't we teach math concepts where each lesson builds on the previous one? The thought of going to a math class where the lessons jump around is intimidating even to me. Why would expect our children to succeed when even we couldn't if put into their places?

Lately there has been a lot of focus on how poorly our schools are teaching children and the fact that changes need to be made. Why don't we start with math? Math teaches critical thinking that is important to future success in learning. Let's overhaul how we approach math and that includes parents and the rest of us. We need to show students what math does for us, how it benefits us on a daily basis. We also need to not translate our negative feelings about math to our children and instead, excite them about this incredibly important skill. Math is the most intimidating subject for many students, and if we can get them excited about it the rest will follow.

## Chemistry in Action - Magnesium and Dry Ice

Don't call the fire department on Professor Yee after watching today's chemistry demo! A school building was actually evacuated once when Professor Yee attempted this demonstration because someone thought the building was on fire! While he creates a large and showy reaction in today's free Chemistry video on Magnesium and Dry Ice, no one gets hurt and nothing is damaged. Instead we get to see what is known as a redox reaction. A redox reaction is an oxidation-reduction reaction or a reaction in which there is a transfer of electrons from one reactant to another. The way Professor Yee accomplishes the reduction is by sandwiching the magnesium between two slabs of dry ice. The beauty of this is we get a reaction that results in a bright white light and a pile of carbon, or graphite, left behind. If you have never seen what happens when you ignite magnesium shavings in dry ice before, check out today's video for an exciting demonstration.

## Chemistry in Action - Natural Acid-Base Indicators

Did you know that you can make a universal indicator out of red cabbage? Amazingly, you can and it's an easy process to boot! Today's free chemistry video is on Natural Acid-Base Indicators. Watch Professor Yee demonstrate how to make the indicator and then use it to test the pH of several household substances. This is a great experiment you can try at home. It's fun to see what colors the indicator turns based upon whether the substance you are testing is a strong versus weak acid or base, or whether it's neutral.  In case you didn't know, a base is a substance that increases the amount of hydroxide ions when dissolved in water. An acid is a substance that increases the amount of hydrogen ions when dissolved in water. So, watch the video, try it at home and make your own acid-base indicator from red cabbage!

## Chemistry in Action - The Fruit-Powered Clock

You may have heard of a potato clock, where a clock is powered by placing metal electrodes into two potatoes. However, did you know that you can make a similar clock powered by fruit that actually works better than potatoes!? They both rely on the same concept of putting a zinc electrode and a copper electrode into something that serves as an electrolyte. The zinc and copper electrodes are the two galvanic cells for the clock while the fruit is the electrolyte. A galvanic cell is an electrochemical cell in which half-reactions of a spontaneously occurring oxidation-reduction reaction are physically separated, generating an electric current.  Learn exactly how all these components work to power a clock in today's free Chemistry video with Professor Gordon Yee. As a bonus, Professor Yee discusses Gilligan's Island and the reality of being able to recharge batteries while stranded on a desert island.

## Chemistry in Action - Slime

Most of us have seen someone slimed on television and many of us have played with the slime that is sold in stores. Slime is an example of a gel, a substance that flows, but also breaks. Slime is derived from polyvinyl alcohol, a polymer made up of vinyl alcohol subunits. When polyvinyl alcohol is is mixed with the chemical sodium tetraborate it creates slime.

You know you want to learn how to make your own slime, so watch today's free Chemistry video with Professor Gordon Yee. He'll demonstrate how to create slime and explain why the chemical reaction results in a gel. This simple, but fun experiment can be easily replicated at home, so watch, learn, and then try it yourself!

## Chemistry in Action - Flame Colors

Have you ever wondered where all the pretty colors in fireworks come from? Personally, I have as both watching and launching fireworks is a blast! From a chemical standpoint, the reason fireworks explode into colors is the result of an exothermic reaction that fuels the electronic excitation of metal salts. Specifically, when the gunpowder blows, it excites metal atoms and then they relax and the energy changes are specific to the metal atom resulting in particular colors coming out. These colors are characteristic of the atom and they give rise to the pretty colors in fireworks. In today's free Chemistry video, Professor Gordon Yee demonstrates this principle by exploding balloons with different metal salts in them. It's a pretty spectacular experiment and if you watch closely, you'll learn exactly what metal salts produce what colors.

## Chemistry in Action - The Electric Pickle

This next Chemistry in Action demo is possibly one of my favorites: The Electric Pickle. Sounds funny, but today's free Chemistry video demonstrates that electrolytes allow a solution to conduct electricity. I don't want to spoil the video, but Professor Gordon Yee wires a pickle and plugs it into an outlet. The resulting reaction is both unexpected and really interesting. In scientific terms, the pickle contains electrolytes that allow the current to flow through it. Make sure you keep an eye out for when he unplugs it to see something you've never seen before: that pickle is SMOKING! Obviously this is something you don't want to try at home, but you can watch the video and see exactly what happens without endangering yourself.

## Chemistry in Action - The Potato Cannon

Potato cannons are incredibly fun. Whether you say potato or potatah, blowing the root vegetable to bits is truly a blast. However, because they utilize combustion to fire an object at high speeds, they can be very dangerous. Well, worry no more because you can play it safe and watch Professor Gordon Yee as he demonstrates his potato cannon in today's free Chemistry in Action video. Our Chemistry course is full of these videos that demo chemistry in action. They'll help you understand concepts you just learned by seeing them applied in the real world.

The beauty of a potato cannon is that it works due to gas laws. When you fire the cannon, the expansion of the fuel after it ignites within the tube forces the potato out of the tubing. This expansion is a result of Charles's Law and Avogadro's Law. In Charles's Law, for a given amount of gas at a constant pressure, the volume is directly proportional to the temperature.  Avogadro's Law states that at constant temperature and pressure, the volume of a gas is directly proportional to the number of moles of gas. So watch today's video and see how when you combine these concepts you'll end up with an explosive cannon that will propel potato-bits at rather impressive speeds and distances.