When you purchase materials, you purchase a single-user license for yourself. This license allows you to distribute the materials to your students via any communication channel necessary for homeschooling (e.g., e-mail, internal school learning management system, password-protected school homepages, etc.). However, you must ensure that only your students have access to the materials for which you have purchased a license.
You may, of course, copy the materials for distribution to your students, such as worksheets.