You may have such question: Why these resources on classtools.net free of charge? What does it rely on to operate well? Yes! The site is supported by Google Ads. So, there is no charge for creating resources with any of these templates. What's more, each template can be saved as a stand-alone HTML file or as a Widget that can be embedded into a blog or wiki.Right now, there are 17 templates that are available for teachers to fill in the blanks and images
. You could go to http://classtools.net/samples/full_list/ to view more.
Classtools.net is a very useful teaching tool for teachers, you could try out it in your online classes.