iPad Apps

[last updated 9/12/2013; short link http://bit.ly/dk-ipadapps]
The problem is not finding apps, but finding the one really good app that does what you need out of the ocean that is Apple's App Store. 

This is a highly biased (and reasonably updated) list of recommended iPad apps of interest to educators. 

Sites with app reviews annotating
techsupportalert.com's  Best free iPad apps - not specific to education; but a site with great reviews and recommendations for free software on any platform. 

ipadapps4school.com - the author (a HS teacher) has been evaluating education-focused iPad apps for years and knows what he is talking about.

appadvice.com - reviews and excellent guides by task; not sure if they play down free apps, but the recommended ones tend to be paid. 

Runners up:
AppsInEducation.blogspot.com apps by discipline with short reviews
The iPad As ... - edtechteacher list organized (with reviews) by tasks a student may need to do 
apps4edu from Utah Educational Network; has good search tool
teachwithyouripad.wikispaces.com - organized by many categories, reviews for some
Kathy Schrock's guide - extensive list with some good stuff
APPitic.com - 1800+ apps for education, organized by many categories, no reviews
Notetaking and PDF annotating
Since notetaking is an important app for high school use of iPads, this category has gotten the lion's share of my time. I've had a few blog posts (my long post and its update) on the subject and have my detailed evaluation matrix on a separate Notetaking Apps page. The best choice for you depends somewhat on the relative importance to you of the various features. My primary focus is on these features:
  • typed notes
  • handwritten notes
  • typed and handwritten annotations of PDF documents
  • automatic synchronization with Dropbox and/or Google Drive
For these features, the best app overall right now is Notability [$1].

If your primary focus is PDF annotating, GoodReader [$5] and iAnnotate [$10] have more extensive sets of PDF features.
Google DocsThe app that handles Google stuff the best is Chrome Browser for iPad. It supports much more functional Google Documents editing than any of the specialized apps, such as GWhiz!, GoDocs, etc. It supports editing Google Spreadsheets but does not display charts. Google Drawings and Presentations can be viewed but not edited. As with Google Sites, using the formatting bar is tricky and frustrating.
Google SitesAny browser works. Editing Google Sites is possible, but using the formatting bar is tricky and frustrating.
Microsoft OfficeFirst of all -- if you haven't tried Google Docs, try them. They are simpler, cheaper and work from anywhere. For 99% of Microsoft Office use, Google Docs works great. And, it is easy to import and convert all your Microsoft Office documents into Google Docs formats. If you want more info, start here.

If you are still in need of MS Office, there are two types of apps -- those that only work when you are online (because they are really running a version of Microsoft Office on their servers in the cloud) and those that work when you are offline. More info about word processing on the iPad is here.

Online:

CloudOn [free] -- you use Dropbox or iTunes to move your files to/from CloudOn. The service runs the free online version of Microsoft Office, which is not as feature-rich as your desktop/laptop.
OnLive Desktop ["free"] -- the free version does not support moving files between OnLive and Dropbox or other online storage. In order to do this, you need the $5/mo version.

Offline:

Quickoffice Pro HD [$20] --  best rated of the offline bunch.

Pages [$10] -- it can handle Microsoft Word .doc or .docx, but I do not know how much it preserves the format.
"Clicker" appsSocrative [free] - take a quick pulse/poll/survey/quiz in class; works on iPad and iPhone; student and teacher versions.
Data plotsDataAnalysis [free] - enter some (x,y)-pairs data, plot them and do some curve-fitting, make a graph from it, and save the result as a PDF or image.

Numbers [$10] - people rave about this one, but it's pricey
Whiteboard A whiteboard app displays the same screen on multiple devices and allows any of the participants to make edits on the screen, e.g. draw, write, type, erase. All the edits are instantly visible on all other users' screens.

PageSend [free] - screencast app and whiteboard app, all in one free package; unfortunately, no Dropbox integration.

[4/30/2012 update]  Bugs, bugs, bugs -- if you have multiple participants, each can work on different pages of the same document only if no one is typing. If typing tool is used, everyone's PageSend app goes haywire flipping between pages.

Multi-iPad Presentation... consists of one presenter and multiple viewers; neither app mentioned allows editing

Conference Pad [$5] - control a presentation (must be a PDF file) on up to 15 iPads. All iPads must have the app installed.

IdeaFlight [free, $7] - similar to Conference Pad

A new kid on the block geared specifically at education is Nearpod [free]. The teacher controls what the students see. The teacher prepares ahead of time a presentation and can intersperse interactive pages -- think of it as a presentation and clicker tool all in one. Interactive pages can contain quizzes, polls or just plain blank page for students' work.

GoClass [free] has the same idea but more features than Nearpod. But! it is still in beta.
Screencasting"A screencast is a digital recording of computer screen output, also known as a video screen capture, often containing audio narration. The term screencast compares with the related term screenshot; whereas screenshot is a picture of a computer screen, a screencast is essentially a movie of the changes over time that a user sees on a computer screen, enhanced with audio narration" [quote from Wikipedia]

PageSend [free] - see comments in Whiteboard above.

Explain Everything [$3] - winner hands down functionality-wise

Screenchomp, Showme, or Educreations [free] - very similar to each other: no Dropbox, share via Facebook/email, no typing. 
Showme and Educreations have no option for varying pen thickness, but both allow to import a picture during the recording. Screenshomp has 3 pen thicknesses, but can only import a picture before the recording starts. If I had to choose one of these three, I'd go with Educreations.
News readerFeedly [free] - has both a magazine-style layout and a text-focused layout.

Runners-up: for magazine-style layout, Zite or Flipboard