Show don't Tell - This card reminds groups to build out their ideas first before they start talking. Educators, in particular, love to discuss, and while discussion is great, sometimes discussion about ideas that are not articulated or formed at all can be a waste of time.
If you are discussing ideas that have actual form and function, the discussion can be more productive. The danger with discussion about ideas that are not built out at all is that the idea is only as strong as someone's ability to explain it. Building an idea can often flesh out all sorts of issues because those issues take shape as the idea is built.
Bonus: Building ideas is fun! Enjoy the process of deciding whether your ideas are good by actually building them.