Why would you want to convince students of something you don't know to be true? There are so many other known benefits to learning martial arts and claiming an increase in IQ specifically caused by practising martial arts is problematic.
There are several theories of intelligence and IQ is just one possible metric, not without its drawbacks.
'According to psychologist Wayne Weiten, "IQ tests are valid measures of the kind of intelligence necessary to do well in academic work. But if the purpose is to assess intelligence in a broader sense, the validity of IQ tests is questionable."'
If you want to say that martial arts improves IQ, then the underlying assumption is that IQ is something that can be changed and that isn't proven. This article is one that outlines many of the problems with establishing whether IQ can be changed. I cite this article only as an example, not as a personal endorsement of the author's view.
My point is that it is an ongoing topic of debate and the major theories of intelligence all have their critics, so there is no easy yes/no answer to your question.