Archive for November, 2011
Looking at science for early elementary (home) school is depressing, and not just because of religious conflicts. This time, it’s just plain old “not knowing the equations”. And really to be fair to the curriculum that we’re using, the errors are all over the internets too, even in some otherwise reasonable references. (And to be fair, there are some that really get it right). What am I so annoyed at?
The speed of sound does not vary based on how close together atoms are. It depends on the stiffness of the material and the density. (the equation is of the form v= sqrt(k/m), where there are various versions of the stiffness, depending on if it’s a gas, liquid, or solid).
Counter example #1: Ice vs water.
Ice floats, so it’s less dense than water (atoms are farther apart), but the molecular bonds are stronger. If the speed of sound was faster when atoms were closer together, then the speed of sound in water would be higher than in ice. But the speed of sound in ice is roughly twice that in water, 3000m/s vs 1400m/s.
Counter example #2. Helium Balloons, inhaled
The molecules in a breath of helium are just as far apart as the molecules of ‘air’, as long as they’re at the same temperature and pressure. The helium is just far lighter and the molecules are going far faster. If you were predicting based on the proximity of the atoms, then you’d expect the speed of sound to remain the same. It’s not, it’s about 3x faster in helium, and so your voice shifts up.
Stiffness and density, vs “how far apart are the atoms”. I’d say that stiffness and density are actually two things that kids can relate to, or at least better than than the distance between something that they can’t see or visualize.
So, what are we to do? Explain it, and demonstrate something else. The speed of beans in sound.
What you’re not hearing here is the end of the 1812 overture, with digital cannons, as played through a subwoofer covered with beans. Click to hear…No comments
So now, I have inflicted linux on the kids. They seem to be adjusting well enough.
Their old computer, a PPC mac mini from before Ben was born, started having issues. The most frustrating one was shutting down when flash was playing on several Very Important Websites (like lego.com), but in general, it was just acting like an old creaky machine. It was set up with the parental controls on safari and mail, and a limited set of applications that they could access, just so that things didn’t get too messed up. I would have liked to replace that machine with an imac, so that it was all in one, less cables to muck with, and generally just fewer pieces. Or a mini, and they could have had the same interface again. But those were all 600$ or more solutions.
So, the lowball approach. One barebones atom MB + case, a stick of memory, usb wifi dongle, and a dvd drive from newegg. Add a drive from my extensive collection of small to med sized hard drives, Monitor, keyboard, mouse, speakers from the old computer, and suddenly, there’s a linux box. I was planning on using the netbook remix from ununtu 10.04 for the interface, but I wanted the wifi to work and some of the more modern stuff from edubuntu on there, so I’m on 11.10. The atom isn’t the most powerful machine, but it’s roughly the equivalent of a decent computer from 4 or 5 years back, and it was only $150.
Which is a little unfortunate. 10.04 was stable, and solid, but the interface there is a dead end and not going to be supported. The netbook remix launcher is gone from any later version, and the whole gnome2 interface is gone as of 11.10. Growing pains it has. It’s mostly ok, just a little confusing. I think the kids might be better at adapting to different interfaces than I am. I’m hoping that the unity interface stabilizes a bit, I’ve seen my share of bugs — layering issues, unity not working for one user anymore, crashes, 600 copies of gnome-screenshot attempting to run at once.
Web filtering is running through a combination of privoxy’s trusted whitelisting and iptables rules to redirect any untrusted user connection on ports 80 or 443 to the privoxy proxy. Firefox is also configured to use the proxy, just to make the connections cleaner on SSL, but it’s not strictly necessary. (github) Mail filtering is going to be whitelisted on the server with procmail or something similar.
I’ve also patched out the unity dash listing of applications for download when searching for an application to run on the machine. They can’t install apps, so there’s no reason to show options to install. Also, there’s no reason that this can’t be a preference somewhere, except that it seems to conflict with the goals of Canonical.
VLC plays movies ripped for the iPad just fine. (At least on the trusted user accounts. Other accounts don’t have access to the movies) Firefox hosts flash just fine, no shutdowns or other issues. Scratch runs well enough that it’s fun to play with. TuxPaint is just like it was on the mac.No comments
Way back when I first got an iPad, I tried connecting a bluetooth keyboard to it to improve the typing and editing experience. My recollection at the time was that the arrow keys didn’t work, and because of that, they really didn’t help the horrendous text editing situation.
In the interim, I have managed to become reasonably good at touch-typing on the wide version of the keyboard. It’s not pretty, and I still have to do a lot of editing, but I’m far better than a two thumb hunt and peck. My most common issue is hitting the return key when I intend to type a single quote, so my text tends to be littered with “can
T” sorts of things that need editing.
So, now I’ve tried again, a few software updates later, and lo and behold, the arrows work. And OMG is it faster and more accurate to type on a real keyboard. Even on the ‘not as good as my beloved Model M 13′ Apple Bluetooth keyboard, I’m typing a good three times faster than on the onscreen one.
iOS 5 fixes a lot of the frustrations I had with the way that Safari did tabbed browsing. (though, I have sort of grown used to the iOS 4 way of doing it). There are now real tabs, that really can open in the background, so I can stack up a few more windows to read while I’m continuing with the first one. It’s also noticeable faster. There is one painful bug that I never noticed in iOS 4 — If you open a news page that you hit frequently, then go to a link from the page, then use the back button, often the cached version of the page is several days old, not the most recent one that you were just viewing.
It would be an interesting experience to see if the iPAD could handle all my on the go sorts of tasks. Adding the keyboard would make ssh far less painful, and it already handles the mail and browsing well enough.No comments
November is the month where I used to stop commuting by bike, at least when I had the option to do it. 40 and Rainy just doesn’t inspire. And so, I don’t think I’m going to manage to continue my summer fitness program, otherwise known as towing the kids to preschool in the bike trailer. I managed it for a good three months, from the middle of July to the middle of October.
It doesn’t seem like much, only 11 miles a couple of times a week. But there are hills (up to a 15% grade). And repetition helps. At the beginning of the summer, I’d been off the bike for a long time, and debating what I needed to do to get back riding. I considered getting a bike with lower gears, just to get up the hills around here even without a trailer (a 39×28 only goes so far). I was considering a triple, or a compact road double. But now, when riding alone, I’m rarely hitting the bottom two gears. I still need the little one when towing a kid, but only on the steepest of hills. Here to Langley is about 18 minutes on my own, a little over 20 with a bare trailer, 23ish with Nate, and 26 with Tim. 10% harder, 10% slower with each increment.
A little at a time. Slow improvement. I know I’m looking forward to being able to do this again when the good weather rolls around again. I can’t believe it took me this long to figure out a good time to go riding with the kids.No comments