The best test of a program for your classroom is to actually have the program in your classroom and, perhaps, to use it with a few of your students. That way you'll know for sure what you are getting and how your students will interact with it. The second best is to preview the software yourself,keeping in mind your classroom, your curriculum and your students.
Different companies have different policies and procedures for preview.
Some will provide titles to almost anyone for a 30-day preview. Some will only provide titles to qualifying preview centers at the district or regional level or at a local university, or they may have a limit on the number of titles you can request. Some do not provide preview copies at all. Read the producer's catalog or contact the producer of the titles you wish to try. In addition, many schools and districts have procedures in place for requesting preview copies.