One of the things that worked incredibly well last year—and which I want to extend this year—is regular vocab quizzes in Geometry.
Vocabulary is the gating factor for success in a problembased, studentcentered Geometry class. If you can't
talk about geometry, you can't
collaborate about geometry.
I learned the value of extremely routinelooking vocabulary quizzes when I taught 8th grade English with Alec MacKenzie, Linda Grady, and Kelly Starnes. At the beginning of the school year, the copy room delivered us each a giant stack of very basic matching quizzes: numbered terms in the lefthand column, lettered definitions on the right. Each student got a vocabulary workbook at the beginning of the school year. Every week we assigned a new chapter/list. Every week we gave a matching quiz. And then we would trade and grade them.
At some level, I recognize that this sounds stultifying. But at another level, it was incredibly empowering for the students. Everybody understood
exactly what was being asked and expected. And everybody saw it as an opportunity to earn free points. Students gave each other encouraging written comments and cheered each other on. They saw their scores as information—not as judgment. They used what they knew to make flash cards or Quizlet stacks. They quizzed each other. They helped each other.
And nobody ever complained about the regularly scheduled vocab quiz. It was a ritual of our course.

Vocab quiz for initial unit on circles 
In my first few years of teaching Geometry, I have noticed that the kids who make the effort to integrate and use the vocabulary and specialized terms tend to succeed. And the kids who don't use the language of geometry suffer. So I decided to use what I know to raise the number of kids who know and use the vocabulary by instituting regular vocabulary quizzes for the relevant lessons or chapters as we go.
Many of my discouraged math learners sprang to life when I assigned this task. They pulled out flash cards, folded sheets of binder paper in half lengthwise, and started organizing the information they wanted to integrate. In most of my classes, I noticed that the higheststatus math students often seemed to get stuck while the weaker students knew EXACTLY where to start and what to do.
It was a revelation.
It also ensured that everybody spent a little quality time on the focus task of preparing for the vocab quiz on Thursday or Friday. And this, in turn, meant that everybody was a little more ready to use the correct and appropriate mathematical vocabulary in our work. They noticed more because the
owned more.
Because these were "for a grade," kids put their shoulder into it. My colleagues in other departments commented about my students taking two or three available minutes during passing period to quiz each other. It gave them hope.
Now I want to create a full set of vocab quizzes for my whole year.
A few implementation notes:
 I collect and shred/recycle all of the quizzes after I enter their scores so I can reuse the same quizzes from year to year. If I don't have your quiz, you can't get a score. I am strict about this.
 Every new vocabulary term does not have to get quizzed, but lessons or units where there is a huge vocabulary burden that gets frontloaded deserves its own vocab quiz. I have been surprised to discover how many lessons are more vocabularyintensive/languageintensive than I had realized.
 Correct use of technical language is selfreinforcing. Once I introduce a new term, I mercilessly ask kids to remind each other of the definitions for 15 seconds in their table groups. Getting one kid to call out the correct definition to the whole class is not the point here. Getting 36 kids to all speak the definitions or the terms in their table groups is.
UPDATE:
D'OH! I can't believe I forgot the most important implementation note I wanted to remind myself about!!!
 There should be many more definitions in your righthand list than there are terms in your lefthand list. Also definitions can be reused. This way there isn't a zerosum outcome if someone misses an answer.