Better Explained

Topics: Math; Programming
Explanation Quality: Better
Medium: Text; Pictures
Type of Content: Educational

Better Explained is a blog whose motto is "Learn right, not rote." I stumbled across it one day while trying to get a better understanding of the number e. (If you want to know what e is, check out the article on it). My experience with e in school was that it was a number that showed up a lot with exponents and logarithms. No one really explained where it had come from. The article I found on Better Explained really helped me understand. It took the explanation one step at a time, using graphs to approach the idea that e is the base for continuous exponential growth.

The thing I like best about this blog is that it helps you get a sort of intuition. The writing style is friendly. The author, Kalid, uses words and pictures as well as math to help you get a sense of what he is explaining.

From the BetterExplained article on Bayes Theorem

The blog has about 61 articles talking about math, with the topics ranging in complexity from arithmetic to vector calculus. But all of them are readable, no matter what your level is. There is also a section on programming and web development. I haven't looked at this part much (I do want to learn more about computers, but that's a goal for next summer when I have more time). From what I have seen, the explanations look similar to those in the math section. There are also some articles with tips on doing some computer things like working with Ruby on Rails and debugging.

This blog is worth checking out if you have a specific topic you don't understand, or if you're bored and want to see a new way of looking at something.

MinutePhysics

Topics: Physics; Math
Explanation Quality: Better
Medium: Video
Type of Content: Educational

MinutePhysics is a YouTube channel focusing on - you guessed it -physics! All of the videos are time-lapsed drawings (it looks like they are down on a white board) with a voice over. The videos are never very long, usually three minutes or less. Two of my favorites are the video on quantum tunneling and the one on round triangles.

Because the videos are short, watching them is a fun way to learn a bit about a lot of different areas of physics. Last year, when the LHC discovered the Higgs Boson like particle, MinutePhysics made a few videos explaining what the Higgs Boson would do and why it was important. Some of the videos cover common physics misconceptions. Overall, I really like the way he both explains and illustrates his points. It really helps my understanding. And since the explanations and drawings often have a bit of humor, that makes me like them even more.

Basically, if I have nothing to do, I can go check out MinutePhysics and consistently be both entertained and educated. So go check it out!

Rising Heat

Hot and Cold

• blue or green colored ice
• red food coloring
• warm water
• large container

Make blue or green colored ice (see the beginning of Mixing Colors for an explanation). Fill the large container with warm water. Make sure the container is as still as possible (as in, not on a rickety folding table). Try to minimize it's movement throughout this activity. On one side drop in a few ice cubes, on the other side put in a few drops of red food coloring. Now observe.

The red is hot water and the green is cold.

You can talk about a few things with this activity. One is why the food coloring spreads out instead of just staying where you dropped it. This is because the molecules in water are always moving. Their movement knocks around the food coloring molecules and causes them to spread out. You may also notice that the red spreads out faster than the blue. This is partly because the blue starts out trapped in the ice, but also because the molecules in the hot water are moving faster. Heat is energy. If you have more energy, you move around more. The same is true for molecules. So the faster moving warm water molecules knock into the food coloring more than the slower moving cold water molecules, thus spreading the color around faster.

The main point of my explanation when I did this was about the layering of the colors (I had this as part of my weather themed activity set). If you don't disturb the water, eventually the red water will be in the top half of the container, and the blue water will be in the bottom half. This is because the blue food coloring is staying with the cool water, and the red with the warm water. The reason the different temperature waters separate is because of density. Density is mass/volume, or how much stuff there is in a certain amount of space. Hot water is less dense than cool water. My friend had a really good intuitive explanation as to why this is true:

Think of a bunch of kids sitting at a table. Right now that don't have much energy, so they stay where they are. Then you give them a bunch of energy. Now they are probably running all around the room, and only a few are still at the table. The kids represent the molecules in the fluid. The energy you give them is heat. The table is the space we're comparing. In the first case there are a lot of kids at the table, or a lot of stuff in the area, so it is pretty dense. In the second kids, only a few kids are at the table so there is less stuff in the area and the density is lower.

Learn More:
http://www.landa.com/docs/HotWatervsColdWater.pdf
http://www.mansfieldct.org/Schools/MMS/staff/hand/atomsheat.htm
http://phet.colorado.edu/en/simulation/density
 

Scientific American

Topics: Science (Biology, Chemistry, Physics, Linguistics, Computer, etc.); Engineering
Explanation Quality: Best
Medium: Print, Graphics
Type of Content: News

Scientific American is my favorite magazine. I've been subscribed for the past three years. I always get really excited when I see that it has arrived in the mail. Every month the have several feature articles on some new, recent topics. Occasionally, the article is themed and all the featured articles are related. For example, the September 2013 issue is all about food - looking at it from nutritional, ecological, and historical perspectives, among others.

They also have specific columns every month, such as the Science of Health and TechnoFiles. I really enjoy SA because it has a nice variety of articles, and I can learn things in fields that aren't my main interest. I also find it convenient that I can bring a magazine with me to read when I don't have internet.

It is also a very reliable source. I don't need to bring my usual skepticism when reading SA because the writers of the articles are (for the most part) scientists who were involved in the research. 

If you can't subscribe yourself, see if your library does. It is also worth checking out their website as they have some full articles there as well.

EdX

Topics: All (Business, Sciences, Philosophy, Economics, Engineering, History, Law, Humanities, etc.)
Explanation Quality: Best
Medium: Video, Text, Powerpoint, Interactive exercises, Problem Sets
Type of Content: Educational

EdX is a collection of free Massive Open Online Courses (MOOC's). If you've never heard of them, MOOC's are courses (normally college courses) that anyone, anywhere can take as long as they have access to the internet. Carnegie Mellon University's Open Learning Initiative is another example of them. However, there are a few key differences. One is that edX currently offers a total of 50 courses from13 different schools. If a course has already finished running, many still allow you to look through the lectures and notes. Most courses will give you a certificate of mastery upon completion. Overall, these are more like taking a real college course, just online.

A screenshot from my Quantum Mechanics class

I am currently signed up for a class on quantum mechanics from The University of California, Berkeley. It runs for 10 weeks. 8 of those weeks are classes, one is a midterm, and one is a final. Every Saturday the material for the next week is released. This is two video lectures (though each is broken up into smaller segments), a copy of the course notes, and a set of homework problems. If you want credit for the homework, it has to be completed by the next Sunday. You can audit any course and simply watch the videos and read the notes, but if you want a certificate, you need to get at least a certain grade. In my course this is an 80%.

There are several other helpful features. The discussion forum is really helpful if you don't understand something. There are also TA's who occasionally post hints or other useful information. In other courses, there can be interactive labs. For example, some chemistry courses have a molecule editor which allows you to "create" molecules in order to answer questions, or just get a feel for how things work.

So far, I really love this site. If you want to learn a new subject, this is definitely a good place to check out. Not all of the courses are entry level though. Each will state its prerequisites on its main page. For example, my course requires knowledge of linear algebra to complete. But it is still worthwhile to check around, even if you don't have anything in particular you want to learn. You map find something that surprises you.

Icy Fun

These activities all involve ice and color to help cool down the last few days of summer.

Some green ice.

Mixing Colors (for young children)

• food coloring
• water
• ice trays (or small containers to freeze the water in)
• bowls/cups (preferably light colored or clear)

You need to make ice cubes in several different colors. To this, first add a few drops of food coloring to some water, mix it, then pour it in the ice tray and freeze it. I assume if you don't mix it, the food coloring won't be evenly distributed, but I haven't actually tried. That might be another experiment you can tie in - seeing how the ice looks when the food coloring wasn't mixed. Have at least the primary colors, but use more if you want!

Then pair up different colors in different bowls. As the ice cubes melt, the colors will start to mix. See if the kids can guess ahead of time which colors will form. Once you've done it with just pairs of colors, try it with three different colored ice cubes.

Rainbow Tunnels

• food coloring (or other form of liquid color)
• salt
• water
• large-ish containers

Freeze several BIG ice cubes using the large containers. If you want your ice cubes to have more interesting shapes, you can fill a balloon or plastic baggie with water and freeze that. You will probably have to leave them overnight. When you actually want to start the activity, do it outside or in a large box - somewhere you won't mind things getting all wet.

Image from artsandcreativity.blogspot.com

 In several small dishes, put a bit of water, salt and food coloring. Set yourself up with a nice variety of colors. Now the fun begins! Start pouring the colors onto the ice. Don't pour too much at once, an eyedropper or even a spoon would be helpful. Also BE CAREFUL. Salt lowers the freezing point of ice, so the ice gets colder . If you have salt on your skin and then put ice on it, you can get a minor form of frostbite. So I would not recommend touching these ice cubes or the salt water colors with your bare hands. It is the salt lowering the melting point that makes this work (it is also what allows you to make your own ice cream). When you add salt the ice immediately around it starts to melt. The salt then slowly melts a tunnel through the ice. If you do this outside, not only will the warmth help melt the ice cubes faster, the light makes the ice cubes look really cool (no pun intended).

Learn more:
http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-cools-icewater.shtml
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch15/colligative.php
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/meltpt.html#c1 

Princeton Journal Watch

Topics: Science
Explanation Quality: Best
Medium: Text
Type of Content: Research, News

Princeton Journal Watch is a blog about research conducted at - you guessed it - Princeton University. Each post gives a description of a recently published research article. They seem to come from all the (science) departments of the university. It is a good way to see what new discoveries are happening. The other great thing about it is that all the posts are written so that a layperson can read them. In other words, even if you don't have background in the topic, you will still understand what the research was about. A lot of the things are really interesting. To get an idea of the type of stuff they have, they last few posts they wrote (at the time of my writing this) are: "Princeton Researchers Use Mobile Phones to Measure Happiness"; "How Will Crops Fare Under Climate Change? Depends on How You Ask"; and "A Faster Vessel for Charting the Brain". All the posts link to an abstract of the article. The only downside is you (usually) can't read the full article without buying it. But I don't mind, because I don't have the background to understand the actual articles anyway. So overall, it's a good place to go for some easy to understand information on complex topics.

States of Matter

These four occur naturally:

Solid: has a fixed shape and volume. The composite particles are very close together and don't move much. Solids can be crystalline or amorphous. Crystalline solids are very ordered. The atoms inside form a repeating structure. Examples are snowflakes and amethyst. There are also amorphous solids. The atoms are very disordered. An example is glass.

Liquid: has a fixed volume, but not a fixed shape. It will fit the container it is in. The composite particles are still close, but they can move around each other more. Examples are water and paint.

Gas: neither a fixed volume nor a fixed shape. It will fill any container you put it in. The particles can be close or very far apart, depending on how much pressure they are under. Examples are water vapor (steam) and oxygen.

Plasma: an ionized gas, full of electrons and ions. Neither a fixed volume nor a fixed shape. Read more about it here. Some examples include lightning and the sun.

Clockwise from top left this shows solid, liquid, plasma, and gas.

However, there are also other things that don't quite fit into any of these categories.

Open Learning Initiative

Topics: Assorted
Explanation Quality: Best
Medium: Text, Practice Exercises
Type of Content: Teaching Material

Open Learning Initiative (OLI) is part of Carnegie Mellon University (CMU). It offers free online courses that anyone can take. While there are only 18 at the moment, they still cover a variety of topics.

There are a couple of things about OLI that I really like. One is simply the style of the courses. They are written in a very accessible way. They are all self-paced. It starts out with a syllabus, and then a brief section with suggestions on how to most effectively use the online course.

The course is mainly composed of written explanations, sort of like those you would find in a textbook. At the beginning of each section is a description of what you will learn in that section. There are little exercises you can do to see if you understand the material (that's the "Did I Get This?" box in the picture). Most of the courses are introductory level, designed to be taken if you have little or no prior experience (or if you haven't thought about the subject in a long, long time).

I have personally been working my way through the Statistics course and the American English speech class. Although I'm only taking the Speech class for fun (technically I'm taking them both for fun, but I do seriously want to learn statistics, I just haven't been able to take a real class at school yet), I find it pretty interesting. To help show the correct way to pronounce things it offers audio files to listen to and diagrams to illustrate what is happening with your mouth and throat. The statistics class is more like a typical math class, with explanations and problems.

This is not a good website if you only need to look up a quick explanation for your chemistry homework. It is a good website if you want to seriously learn about a subject, if you are taking a class in it but your teacher is really bad at explaining so you want another resource you can use simultaneously, or if you found a new subject you think is interesting but you don't even know what you don't know and so have no idea where to start. If any of those sound like you (or even if they don't) it is worth checking out.

Working with Homefront

For the past month or so I have been going down to a summer camp for underprivileged kids to run science activities. It's a really nice place. They spend the morning working on academic things (one day I saw some kids playing math basketball!), and in the afternoon they do more typical summer camp activities like arts and crafts. So I got to come in as a "bonus" academic activity. I took took the kids in smaller groups.

Fun with Glurch

Every time I went I got a different age group.  I first had the teens, then 5th and 6th graders, 3rd and 4th graders, and then the kindergarten through 2nd graders. The first four times I went, I did pretty much the same activity set I did with my other afterschool program. The experiments were matter themed - first we did chromatography and talked about what molecules are and the fact that they move around. Next, we made Glurch and discussed its different properties, and why each one ended up slightly different (because I don't have time to accurately measure the ingredients, so it's all estimating). With the Oobleck, we could talk about states of matter. The straws didn't really relate to the matter theme, but we used them to teach about sound. And it was a nice, not too messy way to wrap up.

HyperPhysics

Topics: Physics, Math
Explanation Quality: Best
Medium: Text
Type of Content: Teaching Material

HyperPhysics is an interactive concept map. You can either search a specific topic, or just find it by following the path. One thing I really like about it is that if in the explanation of a concept, if they use a word for another concept you don't understand, you can follow the link from that word to an explanation of that idea. I find this really convenient.

None of the explanations are very long. They are in nice, manageable chunks. The information is also trustworthy, as it comes from Georgia State University. In general, information that comes from university websites is accurate.

There is also a small side branch of HyperPhysics called HyperMath. It is not as complete of a resource as HyperPhysics is, but can still be useful.

National Night Out

National Night Out is a (presumably national) event held the first Tuesday in August to promote anti-crime organizations and the like. But they also have other community members run booths, and in my town I got to be one of them!

My set-up was pretty similar to that of the local fair I did a few months ago. I was having the kids make Glurch, but I also had a bowl of Oobleck out as a demo they could touch.

Some statistics:
I brought a total of 26 oz of glue, and by the end I had used 18 oz.
I had about 75 kids come by to make something (I only had 25 cups left from a pack of 100).
The colors in order of popularity were blue, green, pink/red, yellow. I actually ran out of blue food coloring.

Here's the sign I put on my booth.

One of the glue bottles was of clear glue. I think I actually preferred it to the white glue, at least in terms of looks. The resulting Glurch seemed a bit stickier and goopier, but I ran out of the stuff before I could really see if that was the case. So sometime soon I want to compare the two (with accurately measured proportions!) and see if there are any differences.

My one big problem with doing the Glurch is that I don't actually measure the amounts out. The cup is filled up to a certain line, but then the water and borax are just kind of thrown in. This makes the proportions slightly different in every batch and leads to some being better than others.

Additionally, with the Oobleck you have to mix it occasionally, because I've found that the water and cornstarch tend to separate.

Unfortunately, this time I forgot the recipie cards. Which is a shame because some people asked me how to make it at home. But I did bring plastic snack bags for them to put their finished Glurch into.

ViHart

Topics: Math, Music
Explanation Quality: Good
Medium: Video
Type of Content: Recreational

ViHart is a self-proclaimed "mathemusician". She makes lots of short, fun videos discussing math and sometimes music. While these are in some sense "educational" they are not going to help you review something from math class. In fact, the set-up for many videos is the doodles you can make while bored in class.

This isn't to say they aren't a worthwhile watch. I love hexaflexagons - I have quite a collection floating around. ViHart shows more of the fun side of mathematics, which is something you don't get to see in school unless you're pretty lucky.

How Much Water Fits On a Penny?

Materials:

• penny
• eyedropper or pipette (if you don't have one this article explains how to make one)
• water
• other liquids
• soap

Make a chart like this (or feel free to copy this one and print it):

Liquid	Predicted # of drops	Actual # of drops
1.
2.
3.
4.
5.
6.
7.

My supplies

For each liquid, you are going to use your eyedropper to carefully drop the liquid onto the penny until it spills over. Record the number of drops that fit. Try and make a prediction before you do it each time.

You can use any and all liquids you want (assuming they are non-toxic obviously). However, make sure you try this with both normal tap water and soapy water. And be sure to wash and dry your penny between each new liquid (and rinse off your dropping device as well).

What's Happening?

The atoms/molecules in a substance are all attracted to each other through intermolecular forces (IMFs). This can be because the molecules are polar (meaning one side is slightly more positive than the other) such as with water. Or it can be because the molecules are big enough that the electrons moving around can induce positive and negative poles. Whatever the reason, when the IMF is between molecules in the same substance, it is called cohesion. So all the molecules on the inside of the liquid are attracted to all the molecules around them. However the molecules on the surface of the liquid don't have any molecules above them to be attracted to, so they are more attracted to the molecules on the inside. This forms a "film" on the surface and keeps the liquid together in a drop.

Since water is polar, and therefore has high IMFs, its surface tension is relatively high. So more water should be able to fit on the penny before the surface film "breaks" and the water spills everywhere.

Image courtesy of factfixx.com

Here's my data chart:

Liquid	# of drops
1.       Water	24
2.       Water	26
3.       Soapy water	23
4.       Milk	22
5.       Salt water	14

Huh... not what I expected at all! Except for the salt water, the number of drops is pretty similar in each. So either the explanation I just gave was wrong, or something happened in the experiment that I didn't account for. Even though the number of drops was the same, I definitely felt suspicious because the blob of soapy water on the penny just didn't look as big as the one from normal water had been. I also felt like the size of the drops were smaller. So since I was using a syringe with volume measurements marked on the side, I filled the syringe up to 1 mL each time and after I had finished dropping on the penny, I continued counting drops until I had emptied the syringe.

So here's my new data table:

Liquid	# of drops	# drops in 1 mL	Ratio
1.       Water	24	23	1.0
2.       Water	26	19	1.4
3.       Soapy water	23	46	0.50
4.       Milk	22	27	0.81
5.       Salt water	14	22	0.64

Now the results make a little more sense. And it does make sense that the drops would be smaller - they have less surface tension to hold them together. I find it interesting though that none of the websites that reminded me of this activity (this isn't the first time I've done this, I actually distinctly remember doing the penny water drops experiment in 3rd grade) mentioned this fact. It might have just been the syringe I used. If anyone else tries this, I'd be interested in hearing how it worked out.

Learn more:
http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html#c4
http://www.chem.purdue.edu/gchelp/liquids/tension.html 

Khan Academy

Topics: Math, Science, Economics, Computer Science, Humanities
Explanation Quality: Better
Medium: Video, Practice Problems
Type of Content: Teaching Material

Many of you have probably already heard of Khan Academy. It is a website offering short videos and practice problems in a variety of subjects. It was originally created to help the creator tutor his cousin over the internet. The videos feature someone (in many it is the founder Sal) giving a short (under 20 minute) explanation while writing it out on the video screen.

There are videos in economics, math, history, and the sciences. There are only practice problems in chemistry and math, but the difficulty ranges from telling time to calculus. I find the practice problems very helpful. The videos are good too. He attempts to explain each thing in several ways, and does examples in the videos. I have one minor problem with them: I often watch videos to review something from class or to compile all the bits I have learned from different sources. So parts of the video are new things/things I didn't understand, and parts I already know. I end up not wanting to watch the parts I already understand, but I don't want to skip forward in case he mentions something else new. But as I said, this isn't really a big problem.

If you make an account, watching videos and doing problems earns you points and achievements which is a fun additional motivator. They also show stats of how much you have been working on skills or watching videos. Personally, I love things that chart my progress.

If you are a parent/teacher/helpful older sibling, you can monitor your child/student/younger sibling's progress. I have my little sister's account registered as a child account under mine so I can make sure she is still doing work over the summer. When I see that she hasn't done her tasks for the day (she is supposed to learn one skill of her choosing every day to make sure she is doing something educational with her time) I can then react appropriately. But don't worry, you don't need a coach or mentor to use this site. It is good for anyone who wants to learn something.

Brilliant

Topics: Math, Physics, Computer Science
Explanation Quality: Good
Medium: Problems, Text
Type of Content: Recreational, Practice Problems

Brilliant.org is one of my favorite math websites. It offers a a new set of problems every week in a variety of topics. Before you start doing problems in a certain topic, you do a few problems to determine your level. The site then places  you appropriately and you can get started with this week's problem set. You level up if you consistently do well.

What I like about it is that the problems are interesting. You don't immediately know how to go about solving something. I always end up with a few problems I can't figure out. At the end of the week, you can view solutions to all the problems. You can also offer your own solutions and help out others who didn't get it.

While the main section of the site has olympiad type problems, there is also a practice section where you can choose to work on specific techniques. It is helpful for reviewing topics from school. It also actually explains methods of solving the problems, instead of just throwing you in there. I personally don't use that section as much, because I have more fun with the main problem sets. There are also smaller weekly problem sets in physics and computer science. I expect the sections to expand in the near future but for now the bulk of the site is math.

So head on over and have some fun!

S'mores at the Speed of Light

Materials:

• Chocolate
• Marshmallows
• Microwave (you will need to know the frequency. If you can't find it the norm is 2.45 GHz)
• Ruler
• Something to do calculations on
• Graham Crackers

 First, if your microwave has a rotating dish in the center, you will need to remove it. Or figure out some way to put food in so it won't rotate. Then lay your bar of chocolate (open it first!) on a plate to place it in the microwave in such a way that it won't rotate.

The red circles are the melted spots.

Image courtesy of Null Hypothesis

Microwave it for a bit, until there are 2 melted patches. 20 seconds should work. Now remove it from the microwave and use your ruler to measure between the two melted spots. Spread the marshmallows out on a plate and repeat.

Sci Show

Topics: General Science
Explanation Quality: Best
Medium: Video
Type of Content: News, Teaching
 
SciShow is a youtube channel run by Hank Green. It posts several different types of videos. There is a weekly video with science news. There are shorter videos on a variety of interesting topics - my favorite is on Non-Newtonian fluids. These offer a quick overview of something.

There are also longer videos which offer more information. My favorite one of those is on epigenetics. Basically, this channel is a good place to learn a bit about a random topic. If you have something specific you want to know about in mind this might not be the right place, but if you just want to keep updated on what's happening in the world, or don't care what you learn about, then this is the place for you. This is not to say that SciShow won't help you if you are trying to learn about a specific topic. I was able to use one of their videos in a presentation on radiation.

The videos are always easily understandable, and normally humorous as well. So go check it out!