Teaching Newton’s second law

I’ve been teaching Newton’s second law to my 6th graders, and I’m really surprised at how the textbooks try to do the math. When I learned it (back before dirt), I learned f = ma (force is mass times acceleration). Our textbook says a = f/m (acceleration is force divided by mass). But I haven’t seen a textbook use this:

Newton's Second Law

With this, all you do is plug in what you know, and it will show you how to get what you’re missing. For example, if you have force and acceleration, you fill them in, and you have force divided by acceleration. That gives you mass.

You can also think about like this: I want to get the force, so I cover up the f. I’m left with mass times acceleration. Or I want to get acceleration, so I cover up the a. I’m left with f over m.

Now, instead of having to remember 3 formulas (f=ma, m=f/a, a=f/m), I just have to remember this one thing that gives me the 3 formulas. All I really need to remember is that force goes on top (because multiplication is commutative).


Teaching with Portals

Portal 2 is a game where you have to use portal guns to create teleportation fields to move around and survive. I’ve head about teachers using it for lessons, especially for physics, but I haven’t had the chance to look into it. There is a website teachwithportals.com which has lesson plans for use with Portal 2. Surprisingly with Language Arts lessons as well as science. I’ll have to look into this.


Last year Mike and I needed to show student growth; that is, how much students learned. We started with giving students a pre test that was the same as the post test. The students really didn’t like this, and just didn’t put any form of effort into it. This was for information that they would soon be learning, so just how useful was it to take a test beforehand that didn’t affect their grade, anyway. I understand. So Mike and I decided to change things and give a benchmark test at the start of every marking period. This test would include 80 questions on the entire curriculum. Students should do better as the year goes on.

The students weren’t as opposed to these, possibly because they didn’t have to take them as often. There were some students who already knew a fair amount of the curriculum, and at the end of the year the average grade was pretty good. It did show solid growth through the year.

This year I’m doing the same kind of benchmark tests. I’ll be tying them into Student Growth Objectives, probably with an objective of a certain average overall grade by a certain date.

Back to School Night

I just had my second back to school night for school yesterday. This year I had two because I had to be at the first one for my four 6th grade classes, and then yesterday for my two 7th grade classes.

It’s good to see that the parents are interested in meeting their kid’s teachers.

The first time I did back to school night 8 years ago was very stressful. I didn’t realize it was coming up until the day before. I was already stressed teaching with some challenging kids, and suddenly I had to stay in the evening and meet their parents. As I recall it went pretty well, and no ulcers were involved.

At this point I have it down to a pretty fast patter and some students mentioned that I was their parent’s favorite teacher. 🙂

Scientists are Romanticists


I just found this quote in an unlikely place. Thought I’d put it here.

A lot of people think that scientists are realists, stacking calculation on calculation to come up with a single truth. But actually, we’re just the opposite. Our job is to look for answers that break down the ideas everyone takes for granted.

It’s a loose way of thinking, one that questions common sense. If anything, it has to be the romanticists that become scientists. A lot of people will tell you, if you like books, you should study humanities.

But if you like to dream, another option is to study science.

— Hayashi Fumino, Angelic Days

I do think that scientists look for things that break down what we take for granted. By trying to find out how our universe works, we’ve found many things that are counter-intuitive, such as: heliocentrism, quantum mechanics, the uncertainty principle, evolution, and much more.

And once you’ve gotten your head wrapped around the new paradigm, you can understand things better. Frequently the new paradigm makes more sense, once you start thinking in its terms.

Sometimes scientists will do an experiment that sounds stupid to do, because we already expected the outcome. But sometimes the result is different from what we’re used to. As Isaac Asimov said:

The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny…’

New students, new grade

Students arrive tomorrow, and while its been a good summer, it will also be good to see the kids again. For the first time I won’t be teaching 8th grade. Instead I’ll be teaching 6th grade, along with half of the 7th. I’m used to half the 7th, but I haven’t taught 6th yet, so it’s a new curriculum for me. Instead of genetics, evolution, and chemistry, I’ll be teaching ecology and the cell. It should be fun. There are some 8th graders that I’ll miss not teaching, but I’ll still see them around. I’m not sure if I’ll be involved with the graduating committee this year; it made more sense when I taught the 8th graders. We’ll see in June.