The title must clearly indicate the purpose of the session (9 wds):

A Visual Pathway for Teaching Idioms to Adult ESL Students (10 wds)

One possibility:

A Technique for Teaching Idioms to Adult ESL Students (9 wds)

Well,,,the "ESL students" part could be considered self-explanitory because it is CATESOL...so maybe:
A three part technique for teaching idioms to adults (9 words)
A technique to help adults use idioms in conversation (9 words)
A technique promoting productive use of idioms for adults (9 words)

OK, I vote for:
A Three-part Technique for Teaching Idioms to Adults (9 words)

We are not specifically discussing conversation or promoting productive use really (other than in general terms). Our technique is mainly about association and recall...which, in theory, would LEAD to those things. --But we are not presenting theories or research or a technique regarding conversation or productive use. Which makes me think that perhaps our title should be:

A Three-part Technique for Introducing Idioms to Adults (9) ????? or maybe

An Initial Technique for Teaching Idioms to Adults (8) ---the idea being that our technique is for use in the beginning stages of teaching idioms.

How about:
An Introductory Technique for Teaching Idioms to Adults (8)

A Three-part Technique for Introducing Idioms to Adults

a preliminary technique for teaching idioms to adults"

A Technique for Introducing New Idioms to Adult Students (9)

An Preliminary Teaching Technique for Introducing Idioms to Adults (9)

A Visual Technique for Introducing Idioms to Adults (8)