How to use the CD-ROM courseware at the back of the fourth grade math teacher's book?
Teachers of People's Education Edition use the CD at the back of the book to open it on a DVD player or a computer with a DVD drive, and play it on a DVD player or a computer with a DVD drive. This CD is encrypted, or the files needed to open the files are not copied to the CD. If you really need it, you can make a mirror image of the CD and open it later with the virtual light area.