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Archive for **July 2008**

If you look for a way to type all of those formula, symbols and Greek letters in Word, you are going to find a package called “Equation Editor.” It is included in Word, but to use a polite term, it’s a bit wonky. The real package with all the functionality you really want is called MathType. It’s not terribly expensive, I bought a copy for home because I do almost all of my prep work at home.

Any copy of Word can run Equation Editor, you need to go to the help tab and search for how to turn it on. There is a couple of steps you will need to do to install it, even though it is already loaded when you load Word.

Since I purchased MathType, they came out with academic pricing that is about half the retail price. It is worthwhile at full price, the academic pricing is a real bargain.

http://www.dessci.com/en/products/mathtype/

Even better, they give you a 30-day free trial. Download and use it, you will be impressed, I promise. If you then go back to Equation Editor, you may want to hang yourself. Leave it to Microsoft to make something simple and great into something buggy and irritating.

If you are new to teaching Physics, you are probably going to expect the students to know how to manipulate numbers and variables. I’ve found that to be a big mistake. Yes, some of my students are very good with math, but I’ve learned not to assume this. As a result, my first two weeks of class are spent working on the skills they are going to use the entire year. Those skills are:

- Scientific Notation
- Estimation
- Significant Digits
- Unit Conversions/Dimensional Analysis
- Solving for variables
- Use of their TI-83 calculators

This is a big post. I have included all of the introductory worksheets, homeworks, and quizzes from the past school year. A lot of example problems I just make up on the fly, but I have attached quite a few word documents. Feel free to use them and adapt them as needed.

**Scientific Notation**

Last year I reviewed estimation first. That was fine until we started dealing with very small numbers, then the students were lost. This year, scientific notation comes first. I have a three part handout that I go over in class. I make up additional problems as we go, then I hand out the worksheet. They start it in class and are expected to complete it for homework.

scientific-notation-notes-part-0

scientific-notation-notes-part-1

scientific-notation-notes-part-2

**Estimation**

The point of estimation is for them to be able to get order-of-magnitude answers quickly. At first, they are completely amazed that I can get within 5% or 10% of the answer faster than they can do it on their calculator. Some of them get good at this, most don’t bother even though they see that I will estimate quickly and accurately throughout the entire year. My goal is for them to realize when their answer on the calculator can be wrong and their brain can be right. It does happen and it feels good when one of them comes over to the dark side with me.

**Significant Digits**

The first document is the handout they get with the guidelines. I think it is rather clear, but I think I want to change the example problem near the end with the sin( ) function. They don’t know sin( ) yet and it distracts them from the operation. I expect them to use these guidelines all year long.

**Unit Conversion/Dimensional Analysis**

Wow are they bad at this. Most of them almost randomly multiply or divide by the conversion to get an answer but never seem to know if it’s right or what the units should be. This is a real problem. The textbooks like to throw different units into the problems. It’s actually easy to miss, especially when the kids are struggling to learn a new concept. I’ve also found that very few of them are comfortable with the metric system. I feel like I beat this section to death, but still many cannot convert correctly.

**Solving for Variables**

I don’t have a worksheet made up for this section. What I have done in the past is gone to an Algebra 1 textbook and copied the problems from there. I gave up on this section last year, they just didn’t have the math skills to do this for every problem, and I had to choose my battles. If they plugged numbers into equations, most of them were able to solve for the unknown.

**TI-83 Calculator**

Here is the problem; the students are unaware of the key labeled EE that does the scientific notation. They also constantly miss the exponent that is shown as 1.2E33. Instead, they enter the number as 1.2 X 10 y^x 33. This works fine if all they are doing is multiplication. However, if they are dividing by the exponent, the 10 y^x 33 becomes part of the numerator. This totally screws up their answers and they have no idea why. There are two solutions: 1) They can use the EE function and only enter exponents in that form, or 2) they can use their longer form and put each term in parenthesis. Obviously, I prefer the first solution and I push them to use it.

I also have them solve simple sine and cosine problems on their calculator. Not all of them use the TI-83, I don’t require it, I only require a scientific calculator. It’s up to them to know how to use it, that is why I spend time in the beginning going over the functions we will use in the course.

The Finish

I give them the following quiz after all of this is completed.

If you have additional material, please share it. Trudi, I hope this helps.

### Conservation of Energy

Posted July 23, 2008

on:This is an experiment I did in my Conceptual Physics class to demonstrate Conservation of Energy. I take a clean plastic peanut butter jar and put in about an inch of copper BB’s. We then wrap the jar in a towel and have a student start shaking the jar as hard as they can. The towel serves two purposes; it stops the transfer of heat from the students’ hands to the jar, and it helps deaden the deafening sound this little activity generates. Use the non-contact thermometer to take a reading of the BB’s before beginning and then after every two minutes of shaking. I usually set up two or three jars and have the students pass the jar to someone else after the temperature is taken. Chart the temperature on the board. Don’t expect to get anything else done while this is happening. There is too much noise and everybody wants to see how vigorously they can shake the jars.

The students are putting energy into the system because they are shaking the jar. They are actually taking the chemical energy from the food they ate and turning that into kinetic energy. The kinetic energy is transfered into themal energy (heat) because of the friction of the BB’s banging into each other. I just thought of this, but it would be a good idea to have another jar set up as a control.

I love Harbor Freight Tools. If you teach science and have one of these nearby, you must get there. The place has tons of tools at bargain prices. They are made overseas, true, but they warranty everything and I have never had a tool fail on me.

The picture on the right is a digital caliper they sell. I use these for a lab on density and also when we are discussing precision. These calipers work great and they are on sale right now for $7.09. Yes, under $10, try getting something like that from Carolina or Frey or one of the other school lab suppliers.

Another item I purchased from them by the hand full are digital multimeters. Again, from the supply catalogs, expect to pay about $80 for one inexpensive meter. At Harbor Freight these babies go on sale for $2.99. I bought a couple for my house, and even though I have a $100 Fluke meter from my engineering days, I tend to take out my $3 meter when I need a reading. Of the ten or so in my classroom, I’ve had one of the leads break in two years of classroom use. I just bought a whole new meter for another $3 and didn’t worry about it.

Here’s another gem, a non-contact thermometer. I got this beauty on sale for $9.99, and I loved it so much I bought another. These are mine, but I bring them in when I need them for a lab. One day I’ll purchase them for the school, I’ve just been lazy about it so far.

You can find all this and so much more. Here’s a few other items I own and use for school: A dual temperature heat gun for $10 (used to launch hot air balloons), a set of six pliers (electronics sized) for about $5, pulleys, sandpaper, and inexpensive but decent castors in all sizes.

You can look up where your local store is located and all the items including sale items at: www.harborfreightusa.com.

### Free Software called Phun

Posted July 21, 2008

on:I just found this package through some random surfing. It’s called **Phun** and it’s a simple graphical world builder with a real physics engine underneath. There is a decent online tutorial and a pretty decent online community to share ideas and solve problems. The download is only 2.8MB, it loads up fast and easy.

Phun can be found here: http://www.phunland.com/wiki/Home

The software was created by Emil Ernerfeldt as part of his masters thesis at Umea University. He calls it a 2D Physics Sandbox and I can see why. You want to take yours shoes off and just play in it all day. Since its creation, Emil has gone to work for a software company where he continues to develop Phun.

Phun is free for an individual to use, but not free for commercial use. Emil made it clear, however, that Phun is free for educational use. I plan to install in on the computers in my classroom and give assignments and perhaps extra credit for designs that demonstrate the principals we are working on in class. There is no reason why my students can’t install the software at home and bring in their creations.

I picked this book up recently at Barnes & Noble for three dollars. It was on the extreme discount rack that occasionally appears near the front door. That day I got lucky with three books on teaching math and science.

I’ve mentioned this in a previous post, but I like to take activities intended for middle school and use them in my 12th grade classes. I find these activities tend to have a higher fun factor and if I find them interesting, at least some of my students should as well.

The book says it contains “over 185 exciting investigations to teach thinking & reasoning skills along with science concepts and facts.” I would agree. The activities are typically only one or two pages long with a small conclusion called “Teacher Information.” The table of contents is one of the most useful I have ever seen. The chapters are divided into topics and each topic has anywhere from five to more than twenty activities clearly listed in the form of a question. For example, under Physical Science and the topic of Energy (of which there are 19 activities), activity two asks, “How Much Horsepower Do You Have?” Then, using only a stopwatch and a calculator, the students use the formula provided to see how their horsepower compares to a motor bike or a car. Simple, but memorable.

Usually, these kinds of books are easy to find. For some reason, this one is not. Nothing on Half.com and the ISBN brought up nothing in a Google search. The author is Marvin Tolman. I have the link to the book in the picture above, but if you go to BN.com or Amazon and search his name, you will find he has a whole series of these books available.

**Summary:** I really like this book for quick activities to start class, another 4/5 Einsteins.

### “Teaching Physics with Toys”

Posted July 16, 2008

on:This is a great resource for a Physics or Physical Science teacher. In fact, this book is within arms reach of me as I type this. I would say it is one of the first places I go when I’m looking for a creative new activity or experiment. The cover says it’s for K-9, but I use it with my seniors and find that the labs and activities are just fine.

I referred to this book in my post about the construction of an electric motor using a D cell, wire, and a magnet. The book is a wealth of ideas and I’ve used it as the starting point of an experiment. I mentioned in the other post that there is an updated version that I have not seen.

**Summary:** Worthy of your shelf space, rated 4/5 Einsteins.

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