Windyty shows beautiful animations of the current wind patterns around the world.
January 2, 2015
December 5, 2014
Calculate the molar mass of a molecule:
The notation for the chemical formula is a little funky: you put the element symbol and then the number of atoms separated by a colon; each element/number of atoms pair are separated by commas, so sodium chloride (NaCl) would be “Na:1,Cl:1“.
This will have to do until I can write something to parse the regular chemical formula notation.
On the plus side, you can link to a specific molecular mass calculation by adding the formula to the url. So magnesium chloride (MgCl2) can be found with this url:
September 5, 2014
So now I can ask a student to draw 23Na+ then show the what they should get:
Draw diagrams of the following atoms, showing the number of neutrons, protons, and electrons in shells. See the example above.
I guess the next step is to adapt the app so you can hide the element symbol so student have to figure what element based on the diagram.
September 14, 2013
My students (almost) created an unmanned robotic drone for delivering messages to the main office.
The robotics students have put together their first robots and are trying out the software for making them move. Lego has a new app that allows you to use your iPhone or iPad as a remote control, and my kids love it. They’ve got a robot fighting competition going on using them as remotes. I, however, wanting to push them into actually programming the robots for autonomous motion, told them I wanted them to get the robot to deliver a message to the front office without them following it through the building.
Well, this was their solution:
They attached an iPhone to one of their robot with the camera facing out. They then connected made a video call to that phone using another phone and the FaceTime app. Since the two phones were busy communicating with each other, the robot was operated using the wireless, Bluetooth connection via someone else’s iPad.
It worked. More or less. The robot lost the Bluetooth connection at the end of the hall, so the robot could not make it all the way to the office.
So now they’re actually trying to write a program. Although I finally got them to do what I wanted, I have to say I was impressed with their innovative use of technology.
March 24, 2013
Try it. You can change the order and coefficients of the polynomial. The default is the second order polynomial: y = x2.
I originally started putting together this interactive polynomial app to use in demonstrating numerical integration, however it’s a quite useful thing on its own. In fact, I’ve finally figured out how to do iframes, which means that the app is embeddable, so you can use it directly off the Muddle (if you want to put it on your own website you can get the embed code).
This app is a rewritten version of the parabola code, but it uses kineticjs instead of just HTML5 canvases. As a result, it should be much easier to adapt to make it touch/mouse interactive.
February 2, 2013
I created this little DNA Writer webpage after seeing the article on scientists recording one of Shakespeare’s sonnets on DNA, I was inspired to put together something similar as an assignment for my middle-school science class to demonstrate how DNA records information. With the website to do quick translations for me, I’ll give each student the translation table and a simple message in DNA code and have them figure out the message.
Update: I’ve adapted the code to add a two to five letter sequence of non-coding DNA to the beginning and end of the message code. There’s also start and stop code as well.
The DNA Writer code uses a simple look-up table where each letter in the English alphabet is assigned a unique three letter nucleotide code. The three letters are chosen from the letters of the DNA bases – AGCT – similar to the way codons are organized in mRNA. Any unknown characters or punctuation are ignored.
Also, with a little tweaking, I think I can adapt this assignment to show how random mutation can be introduced into DNA sequences during transcription. Maybe break the class into groups of 4, give the first student a message as a nucleotide sequence have them copy and pass it on to the next student and so on. If I structure this as a race between the groups, then someone’s bound to introduce some errors, so when they translate the final code back into English they should see how the random mutation affected their code.
UPDATE: Non-Coding (junk) DNA: I’ve updated the code so that you have the option of adding a short (2-5 character) string of non-coding DNA to the beginning and end of each sequence.
UPDATE 2: Personalized and Printable output: Since I’m using the DNA writer to give each student a personalized message, I’ve created a button that gives “Printer Friendly Output” which will produce an individualized page with the code, the translation table, and some information on how it works, so I can print off individualized assignments more easily.
UPDATE 3: You can now get a color coded version of the sequence.
Update 4: Now you can embed the nucleobase color patterns into other websites. Like so:
January 22, 2013
This app lets you drag and drop electrons, protons, and neutrons to create atoms with different charges, elements, and atomic masses. You can also enter the element symbol, charge and atomic mass and it will build the atom for you.
Note, however, it only does the first 20 elements.
February 19, 2011
We were working on plate tectonics last week, and the conversation went from earthquakes to heartbeats.
I think it started with the question of, “How do we know what the inside of the Earth is like if no one’s been down to see it?”
I agreed that we’ve not even been down to the bottom of the crust because the heat and pressure would collapse any hole we tried to drill. I did not mention that terrible movie, “The Core”, because beyond maybe the first ten minutes where there is some actual speculative science fiction, it’s really not worth seeing.
But beneath the crust, how do we know how thick the mantle is? How do we know that the inner core is solid metal (mostly iron) while the outer core is liquid metal?
Not wanting to go into too much detail I tried to explain about seismic waves. Different types can go through different materials and if you monitor their reflections off different parts of the Earth’s interior you can puzzle out the layering and composition. I just gave the simplest demonstration: if you tap a piece of wood with you knuckle, could you tell that it was wood and not metal? What if you tapped a bucket, could you tell if it was full of water or not? Well seismic tomography work in much the same way, except that you’re usually picking up the reverberations from the earthquake rather than making it yourself by hitting the bucket. There’s also a bit more math involved.
But tapping the bucket gives a quick easy feel (pun intended) for the process. My students at least seemed satisfied.
So then I pointed out that you could use an app called iSeismo, to detect seismic waves. Both the iPhone (and its variants) and the iPad have accelerometers that can be used to pick up motion in all three dimensions. My students from last year remembered it, and at least one already had it loaded on his phone.
A quick test showed that the phone’s pretty sensitive. You can pick up two people jumping together all the way across the room. This part of the demo is nice because it helps prove that seismic waves from earthquakes can go very far. You can also see the little squiggles as the waves are picked up.
I did not try it this time, and I’ll need to confirm if it will work, but since the time on the phones should be well synchronized over the network, and iSeismo can output the actual data, we should be able to use three iPhones to triangulate the location of the jumpers. This might work in nicely with geometry now that I think about it.
Anyway, finally, a student asked if the phone might be able to pick up his heartbeat if he lay on his back.
We tried it. Lying on his back on the floor while holding his breath, we could see his heartbeat quite clearly.