Our iPod touch initiative was recently profiled in our school newspaper. We are using them to take notes, to work with our Moodle site, research and do creative writing! Looking forward to utilizing some new apps!!

http://www.lohud.com/apps/pbcs.dll/article?AID=/20091013/NEWS02/910130328&s=d&page=2#pluckcomments

First, the result of the measurement (distance between two locations measured using the phone’s GPS receiver) appears to be displayed to seven significant figures. I believe, given the level of accuracy inherent in the GPS system, is would be more appropriate to display measurements with a resolution of no less than 1 meter (m). (Resolution of 1 foot (ft) could be used in the USA with the understanding that 1 m is a little more than 3 ft.)

The second improvement could be proper use of measurement uncertainty. With GPS Selective Availability turned off (as it is now) the inherent accuracy of a typical GPS receiver system is approximately /- 10 m. (If SA is turned on the inherent accuracy degrades to approximately /- 100 m.) IF the GPS receiver is capable of using enhanced or differential measurements, the position accuracy can be improved to approximately /- 3 m. (These methods include WAAS or Differential GPS - commonly used in surveying or precision navigation instruments - and comparison to locations of known fixed points such as cell phone towers.) For the purposes of discussion I am assuming that the error figures given are 95% confidence values, each standard measurement is made with at least three satellites in the sky more than 20 degrees above the horizon, and for enhanced measurements at least three cell phone towers can be “seen” by the phone, and all measurements are made using the same device. Using standard measurement uncertainty methods, the approximate 95% values for the error of a single distance measurement between two locations are listed below:
Standard measurement, SA on: error = /- 141 m
Standard measurement, SA off: error = /- 14 m
Enhanced measurement, SA off: error = /- 5 m

As you can see, if the estimated distance error is /- 14 m, it is not useful to show a value with resolution of 0.0001 foot (0.0012 inch, 0.03 millimeter)! (It also shows that it’s not necessarily so when the mapping application on my smartphone (not an Apple) tells me that the blue dot indicates my position within /- 3 m.)

If the learning module includes (or the students are already familiar with) statistical methods and spherical geometry, the educator can demonstrate a simple way to improve the measurement uncertainty. At each location, the students could take a series of measurements (at least 5, up to about 20) several minutes apart, find the mean position and its standard deviation, and correct the sample standard deviation using the appropriate value of Student’s t. Then they would use spherical geometry to find the distance between the two positions, and combine the standard deviations to find the uncertainty of the distance.

Error contributors include the orbital mechanics of the satellites, atmospheric distortion and absorption of the signals, the geodesic model used by the device (there are several different ones), the accuracy of mapping corrections to the geodesic model, the amount of sky obscured by buildings or vegetation, the position of the antenna, the time of day (which affects reception), solar weather conditions (which also affects reception) and probably more that don’t come to mind right now.

This is great. I was looking at Comictouch and thought yes we could use this as we are about to have the students using etcha sketch to write maths equations and then save each picture as they write down the numerals one by one to complete the problem. Then we were going to use the pics in garageband and add audio explanations. However we could put comic style explanations on each pic instead. Looks like this will be this weeks trial. My website has more uses of the ipod touch. I can see the iphone would be far more useful as it has the camera and you can record voices.

Cheers from Jenny

PS. Love the graphic use of the iPhone on this page. You are so clever!

There are many schools using the software development kit to write their own applications that tie into their own SIS (Student Information Systems). I saw an excellent one recently for Filemaker Pro.

These apps are all built on the Cocoa Touch API http://developer.apple.com/technology/cocoa.html There were 100,000 downloads of this http://developer.apple.com/iphone/ open-source Software Developers Kit in the first 24 hours of it’s release last year. It took Palm 4 years to acheive similar download.

This is one example of where this is going in T& L environs: http://www.acu.edu/technology/mobilelearning/researchers/video/connected.html