Are you a teacher?, educators or any related with it?, here is I just found a very useful tools for you, all this application are free. You can use it as your teaching activity or just for your daily life. I use some of these apps.
Visit this link, and there are 25 free web application and designed for teacher with tight budget, but the problem is, you must always connected with the Internet connection.
Try it first, and to be comfortable with your activities in teach.
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