Synthesis is defined in research as "the evolution of understanding." The result of this evolution or change is an end result that is new or different. To explain the concept of evolving change, I have use the example of a growing seed.
To help students understand this highly complex cognitive process, I bring in a small bag of seeds. Together we explore the idea of change and growth as we discuss how the seed will blossom and eventually turn into something new or different. We continue to talk about what "ingredients" are necessary for that change to occur.
I am able to then explain this same process happens in our brain. All thinking starts with an idea or "seed." As we add "nutrients" or new information, our thinking grows as well. Over time, we combine our idea "seeds" with new information (ingredients); we will evolve as learners as well.
At some point, the seed in a flower "blooms." This is the moment where we say "Ah!" That's what it is supposed to be. Wow! At points in our thinking, we reach that same "Ah-ha" moment where we say "Wow!" That's it! I Get it?
That is synthesis -- the moment where understanding opens up and becomes clear. When our thinking "blooms," we have synthesized!