I really enjoy using apps that allow you to see your code changes in real time.  I think they are fun for teaching.  I like ICE hosted on http://gamingjs.com/ice/ and W3School ‘s Try it Editor http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_basic . Now Apple has a great looking Swift editor called Playground. Check it out here: http://www.macrumors.com/2016/09/13/apple-releases-swift-playgrounds/

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