When we first started Fostering smaller children, I found it very helpful to subscribe to a Baby/Toddler resources center.
These centers send you free weekly updates on what to expect from a ‘normal’ baby/toddler’s developmental phases and behavior, during that age group. Therefore giving you as a foster parent a barometer to measure ‘normal’ developmental phases and behavior; and when to get professional help for suspect ‘trigger behavior’, and/or delayed development. I found ‘Baby Center’ https://www.babycenter.com/secure/registerBlog.htm very helpful, but there are many others available. Search the net and subscribe. It is such an amazingly helpful, and free tool!