I am a huge fan of Wolfram and the educational resources they provide. One of the things I am focusing on for next year is adapting a CK-12 flexbook for my PreCalculus and Calculus courses. Currently, I am using some of their resources for my Algebra 2 class. The Algebra resources can be accessed here: http://education.wolfram.com/algebra/
You will need to create a Wolfram User ID to access it, but it is free. They also provide educational access to their materials for free, as outlined in their Copyright information (which is also underscored by CK-12's Creative Commons attribution, non-commercial usage) As such, I like to utilize their great visualization resources.
To do this, I want to embed their CDF into my Google Edu sites. However, my students are easily distracted so I want to isolate the section of notes and not send them to the entire Wolfram Education site.
So I embed only the cdf file in the Google Site. There is not a direct link from the Wolfram page. However, I can view the source of the Wolfram page and find the url of the cdf that I want to embed.
For example, I want to use the Textbook section for 12.3 Division of Polynomials in my Google Site.
Like I said, I don't want to distract my students so I right click and View Page Source:
Now I can look the HTML source code for the page and find the cdf file that I want. You need to look for the cdf.embed tag. It is here in the code:
Now the root URL is specified at the top of the page: http://education.wolfram.com and I append the code specified after the cdf.embed, which in this case is /cdf/algebra/TB-12.3-division-of-polynomials.cdf
This yields the URL for only the cdf file:
which looks like this:
Now, I take that URL and embed it in my Google Edu site using the iFrame Gadget. See my blog post on how to do that and allow students to see it. (Obviously, I credit both Wolfram and CK-12 on the Google Edu site. )