Synergy comes from the Greek word that means working together. It describes two or more things working together to produce a result that is not obtainable by each individually and in this case she is referring to facts and concepts working together. She talks about how great teachers prompt their students to think about the conceptual ideas but that they must use facts to support these ideas. The interaction between the factual and conceptual levels of thinking produces synergistic thinking which should be our goal as teachers for developing students' intellects. Concepts are the way we organize the facts - they are the way we prevent information overload of "in one ear and out the other", and only at the conceptual level do we have the transfer of knowledge. source 
chatGPT
Synergistic thinking refers to a way of thinking that focuses on creating solutions that are greater than the sum of their parts. It involves identifying and leveraging the strengths of different individuals or systems in order to create a more effective outcome. Synergistic thinking often involves collaboration and cooperation, as it requires bringing together diverse perspectives and ideas to create a more comprehensive and holistic solution. This can be applied in a variety of contexts, from business and management to science and technology. For example, in the field of business, synergistic thinking may involve bringing together different departments or teams to work on a project, each contributing their unique skills and expertise. In science, synergistic thinking may involve combining different disciplines, such as physics and biology, to create new approaches to understanding complex systems. Overall, the goal of synergistic thinking is to create solutions that are more effective, efficient, and innovative than what could be achieved by working in isolation or using traditional methods. It requires an open and collaborative mindset, as well as a willingness to embrace new ideas and approaches.
DOT FROM preview-next-diagram