Here are a collection of apps that you can customize with your own content for use in classroom centers/stations.
Free iPad app: https://itunes.apple.com/us/app/classroom-dice/id600560907?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/classroom-dice-pro/id602608016?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/classroom-dice/id600560907?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/classroom-dice-pro/id602608016?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/google-earth/id293622097?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/google-earth/id293622097?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.google.earth
Free Mac program: http://www.google.com/earth/download/
Free Windows program: http://www.google.com/earth/download/
Google Chrome app: http://www.google.com/earth/explore/products/plugin.html
Mozilla Firefox extension: http://www.google.com/earth/explore/products/plugin.html
Apple Safari extension: http://www.google.com/earth/explore/products/plugin.html
Free iPad app: https://itunes.apple.com/us/app/free-graphing-calculator/id378009553?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/free-graphing-calculator/id378009553?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/scientific-graphing-calculator/id369480853?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/scientific-graphing-calculator/id369480853?mt=8&uo=4&at=10l6SU
Website: http://dictionary.com
Google Chrome app: https://chrome.google.com/webstore/detail/dictionary-by-dictionaryc/gikhgcaliglmioibbockkmjknfnepbdh
Website: http://thesaurus.com/
Google Chrome app: https://chrome.google.com/webstore/detail/thesauruscom-synonyms-and/clljlcapeomdokpgadmegpabakieebci
Free Android Phone app: https://play.google.com/store/apps/details?id=com.merriamwebster
Paid Android Phone app: https://play.google.com/store/apps/details?id=com.merriamwebster.premium
Free iPad app: https://itunes.apple.com/us/app/merriam-webster-dictionary/id438477986?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/merriam-webster-dictionary/id478132032?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/merriam-webster-dictionary/id399452287?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/merriam-webster-dictionary/id478126577?mt=8&uo=4&at=10l6SU
Website: http://www.merriam-webster.com/
Free iPad app: https://itunes.apple.com/us/app/educreations-interactive-whiteboard/id478617061?mt=8&at=10l6SU
Website: http://flowboard.com/
Free iPad app: http://itunes.apple.com/us/app/puppet-pals-hd/id342076546?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/showme-interactive-whiteboard/id445066279?mt=8&uo=4&at=10l6SU
Website: http://www.showme.com/
Free iPad app: https://itunes.apple.com/us/app/id412443803?mt=8&at=10l6SU
Paid Windows program: https://doceri.com/win_doceri.php
Paid Mac program: https://doceri.com/download_form.php
Paid iPad app: http://itunes.apple.com/us/app/popplet/id374151636?mt=8&uo=4&at=10l6SU
Paid iPhone app: http://itunes.apple.com/us/app/popplet/id374151636?mt=8&uo=4&at=10l6SU
Website: http://popplet.com/
Free iPad app: https://itunes.apple.com/us/app/simplemind+-mind-mapping/id305727658?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/simplemind+-mind-mapping/id305727658?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/simplemind-for-ipad-mind-mapping/id378174507?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/simplemind-for-iphone-mind/id304515487?mt=8&uo=4&at=10l6SU
Free Windows program: http://www.simpleapps.eu/simplemind/desktop/windows
Paid Windows program: http://www.simpleapps.eu/simplemind/desktop/windows
Free Mac program: https://itunes.apple.com/us/app/simplemind-free/id439654198?mt=12&uo=4&at=10l6SU
Paid Mac program: https://itunes.apple.com/us/app/simplemind/id434808346?mt=12&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.modelmakertools.simplemindfree
Paid Android Phone app: https://play.google.com/store/apps/details?id=com.modelmakertools.simplemindpro
Free iPad app: https://itunes.apple.com/us/app/classroom-timer/id570172806?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/classroom-timer-pro/id594124231?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/classroom-timer/id570172806?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/classroom-timer-pro/id594124231?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/ibrainstorm/id382252825?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/ibrainstorm-companion/id382260522?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/pixntell/id532075424?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/pixntell/id532075424?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://market.android.com/details?id=com.evernote.skitch
Free iPad app: http://itunes.apple.com/app/skitch-for-ipad/id490505997?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/app/skitch-for-ipad/id490505997?mt=8&uo=4&at=10l6SU
Free Mac program: http://itunes.apple.com/app/skitch/id425955336?mt=12&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/haiku-deck/id536328724?mt=8&uo=4&at=10l6SU
Website: http://www.haikudeck.com/
Free iPad app: http://itunes.apple.com/us/app/screenchomp/id442415881?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/make-dice-lite/id379873571?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/make-dice-lite/id379873571?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/make-dice/id353484349?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/make-dice/id353484349?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/geoboard-by-math-learning/id519896952?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/geoboard-by-math-learning/id519896952?mt=8&uo=4&at=10l6SU
Website: http://www.mathlearningcenter.org/web-apps/geoboard/
Google Chrome app: https://chrome.google.com/webstore/detail/geoboard-by-the-math-lear/gaakmmdiopnmcenkojohldanladpajak
Free iPhone app: https://itunes.apple.com/us/app/videolicious/id400853498?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/videolicious/id400853498?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/bill-atkinson-photocard/id333208430?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/bill-atkinson-photocard/id333208430?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/tellagami/id572737805?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/tellagami/id572737805?mt=8&uo=4&at=10l6SU
Free iPad app: http://itunes.apple.com/us/app/id418451914?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/id418451914?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/pic-collage/id448639966?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/pic-collage/id448639966?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.cardinalblue.piccollage.google
Free iPhone app: https://itunes.apple.com/us/app/sock-puppets/id394504903?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/sock-puppets/id394504903?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/stick-pick/id436682059?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/stick-pick/id436682059?mt=8&uo=4&at=10l6SU
Paid Android Phone app: https://play.google.com/store/apps/details?id=com.buzzgarwood.stickpick
Free iPhone app: https://itunes.apple.com/us/app/tinytap-moments-into-games/id493868874?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/tinytap-moments-into-games/id493868874?mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=it.tinytap.market
Free Android Tablet app: https://play.google.com/store/apps/details?id=it.tinytap.market
Website: http://www.tinytap.it/games/
Free iPad app: https://itunes.apple.com/us/app/ibooks/id364709193?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/ibooks/id364709193?mt=8&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/scribble-press-creative-book/id999929385?mt=8&at=10l6SU
Paid Android Tablet app: https://play.google.com/store/apps/details?id=com.fingerprintplay.scribble2paid
Free iPhone app: https://itunes.apple.com/us/app/doodle-buddy-paint-draw-scribble/id313232441?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/doodle-buddy-for-ipad-paint/id364201083?mt=8&uo=4&at=10l6SU
Website: http://www.classdojo.com/
Free iPad app: http://itunes.apple.com/us/app/classdojo/id552602056?ls=1&mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/classdojo/id552602056?ls=1&mt=8&uo=4&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=com.classdojo.android
Google Chrome app: https://chrome.google.com/webstore/detail/pbinoojbbajacmkigmfnkclhgjnglpon
Free iPad app: http://itunes.apple.com/us/app/timestation/id468529107?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/timestation/id468529107?mt=8&uo=4&at=10l6SU
Website: http://www.mytimestation.com/
Free iPhone app: https://itunes.apple.com/us/app/stop-go!/id506877227?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/stop-go!/id506877227?mt=8&uo=4&at=10l6SU