February 2011 Archives

Biology - Protein Synthesis

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We just shared a video on Translation and Transcription, and today's free Biology video is an overview of Protein Synthesis, the process in which cells build proteins. This is a complex process and difficult to cover in a single lecture, but Professor Wolfe takes the challenge head on in today's lecture.

Protein synthesis is a 4-step process that starts with the transcription of mRNA from a DNA gene in the nucleus. Then, initiation begins when the mRNA codon, AUG, binds with the initiator tRNA anticodon, UAC. After initiation, elongation starts when a second tRNA anticodon binds with the appropriate mRNA codon. The process repeats until the ribosome encounters a stop codon, which causes the release of the polypeptide and the break up of the ribosome.

This is a lot to take in and it's a good thing Professor Wolfe is such a great teacher because he makes it much more understandable than I can.  Definitely check out today's video and learn more about protein synthesis.

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Biology - Transcription and Translation: An Overview

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The central dogma of molecular genetics is that information flows from DNA to RNA to protein. Transcription is the process where information on DNA is coded into a messenger RNA molecule. A simple way to see transcription is that it involves rewriting information. Translation is when information on the messenger RNA molecule is converted by a ribosome into a polypeptide strand. In other words, translation converts the information into usable language.

In today's free Biology lecture, Professor George Wolfe compares and contrasts transcription and translation. He explains the variation between these two processes in prokaryote and eukaryote cells. One of the biggest differences you'll notice is that translation and transcription are not segregated in prokaryotic cells. However, in eukaryotic cells, transcription occurs inside the nucleus while translation occurs outside of the nucleus. He then discusses the machinery for transcription and translation, the three kinds of RNA: mRNA, tRNA, and rRNA. Learn more about these types of RNA and what happens during transcription and translation in today's video.

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Physics 1 - Weight

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In everyday language, the words "mass" and "weight" are often used interchangeably. However, they are not the same thing and it is important to differentiate the two terms in physics. Mass is the amount of material an object contains, a measure of an object's inertia. Whereas, weight is the force of gravity exerted on it.

In today's free Physics 1 lecture on Weight, Professor Steve Pollock will demonstrate the difference between mass and weight and how to determine weight when mass is known. He'll discuss the impact of outer space and its low gravity on weight. The concept of weight is an important one. Distinguishing weight and mass is obviously important if you're going to use Newton's Second Law. The quantity which you're interested in when your working dynamics problems is the mass of the object.

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Online Video Sharing Solutions for Parents and Teachers

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A few weeks ago, I was trying to help a teacher over Twitter who was having issues setting up a place where her students could post videos for her to review as part of a class project. YouTube wasn't an option because her school was blocking it. My suggestion was to try TeacherTube, a site similar to YouTube but for instructional videos only. The education population has embraced it for what it is: a school-focused YouTube minus the questionable content. Unfortunately, she responded that her school blocked that site as well, which shocked me, as the site is truly dedicated to education. My only guess as to why the school blocks it is that it has ads that help pay for the site. Many schools are careful about blocking sites with ads to better control the content being seen--which makes perfect sense to me, since it's not uncommon to visit a site and be shocked by the ads.

The fact that I couldn't find a solution for this teacher bothered me. And while I wished the school would allow access to a positive site like TeacherTube, I knew deep down there had to be something else. Well, I spent some time researching and found a few possible solutions. Many of these sites are perfect not just for teachers, but also for parents wanting to let their children watch educational videos while protecting them from ads and inappropriate content.

SchoolTube is very similar to TeacherTube. It's a video-sharing website targeting students and educators. They claim their website is exclusively endorsed by leading education associations, but the big bonus is no ads. You can create your own channel to share videos and watch some of the great videos other schools, students, and teachers have made. This has great potential if you have budding filmmakers who want to test their skills on education videos and share with others in a safe environment.

Lectr is like SchoolTube in that you can upload videos, create groups, and watch videos. The big difference is it targets junior-high and high-school students, and the content is reflective of that. Unfortunately, there are ads, but there are also some great lectures that are perfect for this age group.

I then found my favorite solution for anyone wanting to utilize the massive educational library of YouTube but needing to filter out objectionable content. Primary School pulls videos from YouTube and a variety of sources, filters any questionable results, and presents each video in a completely ad-free space. That level of attention makes me hopeful most schools won't block it. I like the idea of using this with YouTube; students could upload videos onto YouTube at home, and then teachers could share these videos with the class via Primary School.

These are some great resources for dealing with students and online video. As video becomes more and more common in the classroom and as schools place such tight restrictions on where teachers can go online, I can't help but wonder what else is out there to solve this problem. What sites have you found that enable you to view and share videos without inappropriate content and/or ads? 

Biology - Mitosis vs. Meiosis

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For some people, the difference between mitosis and meiosis is confusing. This is not surprising as the names are fairly similar and both involve cell division. However, meiosis is only for the formation of gametes, or sex cells while mitosis is for everything other than sex cells.  Both involve the replication of DNA and involve the following phases: prophase, metaphase, anaphase, and telophase. However, only meiosis involves synapsis, or when chromosomes associate to form homologous pairs. Homologous chromosomes are chromosomes that have the same genetic composition and are derived from different parents. Professor Wolfe continues to compare these two processes of cell division in today's free Biology video on Mitosis vs. Meiosis. We'll let him show you the rest of the differences and similarities between the two different types of cell division.


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Biology - An Overview of Mitosis

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We all know biology has a lot of vocabulary. You'll definitely get a dose of it in today's free Biology video on Mitosis: An Overview. However, it's more important to understand the different stages of Mitosis and the different cellular events that occur during it. Believe it or not, a cell spends only 10% of its life dividing and some never divide. So, as important as Mitosis is, it isn't a constant occurrence in a cell's life. Most of its life is spent in the interphase stage, the period when a cell isn't actively dividing.

Mitosis is mainly about forming chromosomes, which is why DNA is only packed into a chromosome when a cell is going to do Mitosis.  But did you know that chromosomes could form in three different ways? Depending on where the centromere, or the pinched-in section in a chromosome is, determines what type of chromosome it is. A telocentric chromosome has the centromere at the top or bottom, an acrocentric chromosome's centromere is off-center, and the metacentric chromosome's centromere is centered. Seems like a lot to remember, but what is most important is to understand what is actually happening during Mitosis. Watch today's video and let Professor George Wolfe explain the process and, as he says, the vocabulary will come later.

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After watching our videos on Newton's laws, it's a good time to start looking at how to use these laws to solve physics problems. Today's free Physics 1 lecture begins with a demonstration of tension with a rope. As we know, forces are pushes or pulls. Tension is a stretching or staining force, a good example being the force applied to a rope. The greater the tension, the more force on the rope.

Professor Pollock then shows that if a rope is massless, the net force on it is zero because the force on one end of the rope is equal in magnitude and opposite in direction to the force on the other end of the rope. Whew! You'll see exactly how this works when Prof. Pollock proves it using the F=ma equation from Newton's second law. He'll then demonstrate how pulleys change the direction, but not the magnitude of forces on ropes.

Professor Pollock also provides a good method of solving any problem using Newton's second law: drawing a force diagram. Creating a force diagram involves drawing the situation and noting all sources of force on the object.

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Physics 1 - Actions, Reactions, and Newton's Third Law

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Newton's laws are key to understanding motion and how forces on an object can impact its motion. So far all the laws have been about a single object and the impact of outside forces upon it. With the first law, Newton showed that a body in motion remains in motion and a body at rest remains at rest. The second law stated that the acceleration of an object is dependent upon two variables: the net force acting upon the object and the mass of the object. With his third law, Newton focused on what happens when a body exerts a force on a second body.  You probably have heard this in its simplest form: "For every action, there is an equal and opposite reaction." Watch as Professor Pollock demonstrates Newton's Third Law in today's free Physics 1 video. Also, don't forget to check out a past Physics in Action video that gives you a better look at how Newton's third law works.

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Physics 1: Introduction to Newton's Second Law

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In today's free Physics 1 video on Newton's Second Law, Professor Pollock uses an air track to demonstrate once more Newton's First Law: basically an object at rest stays at rest and an object in motion stays in motion. If you haven't seen one before, an air track is a structure where air is pumped through a hollow track with holes along it that allows air track carts to glide relatively friction-free. The concept is similar to an air hockey table as the air removes friction so objects move more freely. With the track he shows that when you add force to an object you increase its acceleration. Weights are then added to the cart to demonstrate acceleration is inversely proportional to mass. The goal of all these demonstrations is to prove Newton's Second Law, an equation, F = ma, which explains why objects accelerate and is the centerpiece of Physics 1.

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Physics in Action: Toss-and-Catch from Two Points of View

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What does it mean when we say that motion in the horizontal direction is independent of motion in the vertical direction? Today's free Physics in Action demonstration: Toss-and-Catch from Two Points of View looks to answer that question. In the experiment, a cart is placed on a track so it can only move in a horizontal direction. Within the cart is a ball that can be ejected in the vertical direction by tripping a spring on the cart. We know that if the cart is not moving, the ball will land in the same location from which it was launched. However, where will the ball land if the cart is moving in the horizontal direction when it is launched? There are a few possibilities including:

1. The ball drops in the exact spot it was launched from, or
2. The ball moves at the same horizontal speed as the cart and lands in the cart.

Watch the demonstration to find out exactly what happens and why.

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iPads in the Classroom: The Future?

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I was reading an article about the use of iPads in the classroom, and it really convinced me what a great solution iPads, or any other tablet computer, are for bringing technology into the classroom. Of course, I see the benefit of this technology allowing for more inverted learning, which, as we've mentioned before, is a method Thinkwell truly supports. I also see this as a way for more students to be exposed to better teachers like our own via online courses and apps like our Calculus app for the iPad.

The author writes about visiting a pilot classroom where iPads are being utilized as a teaching tool. The author, Tina Barseghian, found that while the iPads were being used to watch videos, the teacher was still key and the focus of the classroom was on enrichment and individualized learning instead of just lecturing.

However, I was shocked by the negativity I saw from the very first comment: "That kids love learning by watching videos is nonsense. Who wouldn't rather zone out watching a video instead of listening to a teacher?" This commenter had much more to say, but to me it was clear that this person has never come in contact with learning by video. They had never seen any of our videos on YouTube or even heard of the Khan Academy. They hadn't seen the many comments from students who felt these videos helped them where their teacher or textbook did not. This person also didn't consider the fact that if a student hasn't watched the video, it will become obvious in class when the teacher attempts to build on what the student should have already learned.

The comment that got me the most was someone complaining that the following statement should make every parent angry: "Let students cover the basics on their own, and let teachers delve into enrichment and individualized learning. That's what the good teachers are telling me." My assertion is this should make parents happy. This system helps ensure students don't get left behind and instead allows teachers to focus on the students who need help. As students move forward, more and more of their education becomes their own responsibility. No one in college holds you by the hand and leads you through learning. Instead, you are given lectures and textbooks and expected to succeed. Wouldn't a system that encourages students to cover the basics on their own also teach a student to succeed in college--not to mention in life?

Of course there were several comments from people who recognized the value of technology in learning and appreciated how it allows children to dig deeper into subjects. One person even pointed out how grateful he was that the iPad replaced the fifty pounds of books their children were carting around in their backpacks.

Folks, what we're seeing is an evolution in education. And people are very resistant to change, especially when it involves their children. But as with all large changes, I think we'll see these early adapters begin to show improvements and slowly bring the protesters on board. What do you think about the direction technology in education is going, and where would you like to see it go?

Physics in Action: The Hunter and the Monkey

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We have focused on projectile motion in the last two videos we posted. Now it's time to see a demonstration of projectile motion in action. In today's free Physics 1 video, we're going to see The Monkey and the Hunter experiment. This demonstration illustrates the effect of gravity on projectile motion. Basically, we've got a hunter who spies a monkey hanging in a tree. The monkey decides to release its grip the instant the hunter fires his gun thinking he'll fall below the trajectory of the bullet. Of course, the monkey doesn't know physics and has forgotten the importance of gravity on projectile motion. Watch the demonstration to see what happens next!

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About this Archive

This page is an archive of entries from February 2011 listed from newest to oldest.

January 2011 is the previous archive.

March 2011 is the next archive.

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