I thought this prompt of free tools was intriguing and I encourage you to read Musicuentos.com post, “Supporting the Community.”
My absolute favorite free web tool is Google Image Search. It revolutionized my lessons- being able to pull in images on anything at any given time. But that’s not a very interesting or unique tool. (However, if it went away I would cry.)
My real free tool is Edpuzzle.com. This has also revolutionized my lessons. Edpuzzle allows me to add questions to video, either uploaded by me or pulled from any number of sources, including YouTube. I can have students watch a video at home and ask them comprehension questions about it. I can differentiate the same video and have a challenge version. It links to my Google Classroom so all of my students are enrolled and I can see who has or hasn’t watched the video. I can make it so they can’t skip ahead; I can make it so they can. I love the versatility of Edpuzzle.com to add in authentic videos with questions.