You bring up an important concern that many elementary teachers have when they are given a science textbook and no professional development on how to incorporate the reading material with other resources that might be available either in the way of kits or online resources through the text book companies. There are a few online science textooks now that attempt to include a plethora of resources that are often daunting to try to digest in order to implement.
Don't hesitate to contact textbook companies and ask for help! That should be something they are willing to do if they want to have 'happy' customers. In the meantime, the NSTA has a wealth of hands-on resources on all of the science content areas. It may be up to you to sift through and find just the right one for a particular topic in order to help your students investigate the phenomenon and make sense of it. Identify what the standard is for the textbook content, and search for a hands-on lesson that focuses on that phenomenon in the standard.
Best wishes for a highly successful and effective teaching career!