read from the same page
To have the same understanding, thought process, or amount of knowledge (about something) as someone else. We all need to be reading from the same page before we try to present this idea to the boss. I think it would help if both parents attended the presentation. That way, you'll both be reading from the same page when it comes time to implement what we talk about.
read from the same page
and sing from the same hymnbookCliché share the same understanding of something. Okay, I think we are reading from the same page now. We can discuss the future of this project more productively.