Go Math! does make its textbooks available online at hmhco.com. The online textbook editions are available for grades K-8, and are formatted with the same material as the original textbooks along with some limited interactive learning tools.
The Go Math! e-textbooks work with most tablets, making it a convenient tool for the classroom. Online editions, which are meant to be used with desktop, laptop and net book computers, are another choice and are available for grades K-8 as well. The online editions contain the same material as the original textbook plus additional interactive learning and assist tools for working with the textbook at home.