For a church class, taught from the traditional approach, I would use a book that has some sort of narrative. There are several classical grammars that take this approach: Athenaze, JACT series, Reading with Thrasymachus, et. al. Using a reading approach, rather than studying different grammatical categories and unrelated simple sentences, is much more rewarding, and you get people reading early on, and more immersed in the language. Mounce is nothing but charts and declensions of nouns for the first 8 weeks. The workbook mixes English and Greek in the sentences so the learner has to constantly 'switch' languages mid sentence frequently which is not the way to learn.
There are very few NT grammars written from a narrative approach (also called inductive): Dobson's book is titled Learn New Testament Greek. (Use the 3rd edition -2005 - as the accents have been added to the text)(See the thread http://www.textkit.com/greek-latin-forum/viewtopic.php?f=23&t=9389
). Clarence Hale's Let's Study Greek (out of print) - I can send you some sample shots if you email me.
I'm teach in a Koine Greek group that teaches in several churches and has about 5 beginning Greek classes each year. It's been going on for 28 years, and I've taught for about 7. Lately I've switch to active learning methods (cf. Randall Buth's BiblicalLanguageCenter.com). Most people in my group use an abridged version of Hale. And several have used Mounce. The problem with teaching in a church is that there is often little commitment. People come unprepared to class, skip a week or two, and expect to be able to catch up, which then ends up slowing you down because you really do want to keep the class size at max. You need to let people know that it takes about 400 hours of study to master a 1st year level of language - then hope to get them to study 3-5 hours per week. We do not quiz students. Ask for a small financial commitment - $25-$50 for copying, etc. Let them know book costs up front ( A reader's GNT costs about $40). Expect dropouts about 6 weeks in, and then again over the Christmas break. If you can keep people into January, you will have them for the rest of the year.
1st class, teach the alphabet, give a little history of Greek and why it is important. I have people read Leland Ryken's Choosing a Bible: Understanding Bible Translation Differences http://www.christianbook.com/choosing-a-bible-understanding-translation-differences/leland-ryken/9781581347302/pd/47304
. If you hunt it may be available for free as a pdf online. Then teach the 1st chapter in your book (which is usallythe alphabet). The first class will whiz by if you are prepared.
If I had to teach from the 'traditional' approach, I would use Dobson's book.