I have always wanted to do the hydrogen gas/oxygen gas balloon explosion in class, but it isn't very practical or very safe. Once again Steve Spangler shows a much easier and safer way to do the reaction. Of course I had to try it myself and it works beautifully. Making the egg hollow is quite easy as shown here. The most common chemical reaction taught to middle school students is 2H2 + O2 ----> 2H2O. They rarely see it live though. They also have a hard time understanding that water gas is produced by this explosive exothermic reaction (the same chemical reaction that is used in the space shuttle main engines).
This is a new variation on my "Fire Hand" demonstration. I never did like the size of the methane bubbles that were produced, so I got an idea from a Mythbusters' segment on methane bubbles. They used a tube with many small holes to create the small methane bubbles. I decided to to do a variation of it using aquarium tubing. The result is a bigger handful of methane bubbles which means a bigger flame!
A major standard our students have to learn is the difference between elements and compounds. Compounds are substances that are made of two or more elements bonded together. The elements that comprise a compound have different properties when they are bonded together than when they are separated. Students have great difficulty with this. I introduce the unit by doing a simple activity on mixtures. Educational Innovations sells a simple Mixture Separation Challenge kit. Students are first forced to separate the mixture into 3 groups. Students usually use the simplest property of color to do it. There are other properties such as relative density or optical properties (opaqueness, transparency, etc.). The main idea is that the substances can be separated by their properties, because those properties do not change when forming a mixture, unlike when a compound is formed.
I found a new way to teach the conservation of mass/matter this past year. Previously I taught it by having steel wool (iron) react with oxygen. Since our periods are shorter this year, I couldn't really do that reaction anymore. Now students mix heavy whipping cream and vinegar in an open system. The vinegar reacts with the casein proteins in the heavy whipping cream to form a solid cheese-like substance (basically it is cheese). It's not a very glamourous reaction, but is also a way to teach students about precipitation. Students have a difficult time understanding the concept of two liquids reacting to make a solid. This is a simple way for students to visualize that type of chemical change.
State testing is late in the school year which means that we get to spend only about two to three days on our last unit, astronomy. Luckily this year we have what's called a science reading enrichment period. It allows us to cover more in depth some of the concepts that we don't usually have time to do. This past couple of weeks, we got to cover some astronomy. In the last few years, students have been asking me numerous times two questions: "Why isn't Pluto a planet anymore?", and "Did you hear about the 10th planet?" Normally I would quickly have to answer these questions without students investigating themselves. This time I decided to use a method of inquiry used by Veritasium.
Derek Muller, the main host of the videos, usually goes to the streets and asks questions to ordinary people about a particular science concept. It is fascinating watching people try to verbalize and work through their thinking during the interviews. At the end Derek reveals "the answer" to the main question with easy to follow explanations. I wanted to incorporate that kind of inquiry into my class.
I decided to ask the question, "what makes a planet a planet?" to some of my fellow (non science) teachers. My plan was to ask a question that many people are familiar with, but have a hard time with the definition. I then wanted to show the video to my students so that they can see that this question is hard for learned adults as well as for students. Students then had to write their own definition of a planet and share with the class. I then gave them reading materials and showed a couple of videos that dealt with the concept. Then the students came up with their final answer and then had to share their results by speaking to the camera. The above video shows the teachers' responses and the students' responses to the teachers.
Friday, December 30, 2011 at 3:46PM 