Angels have training sessions, just like humans.  We often think they are all-knowing, but the Bible tells us otherwise. (1 Peter 1:12)
In Chapter 4, we join an angelic training session for those that will be assisting humans during the next move of the Spirit for healing.  We hear from angels that assisted those with the gift of healing in the last healing revival and met the two angels that will assist Anna in healing when the outpouring begins.