If you have read all four installments of this series, hopefully you have some ideas that will help you when teaching any one of the age groups. However, the real challenge is putting together a lesson which works for a combined group that spans all the ages.
The good news is that most of the advice given for specific age groups also applies (to greater or lesser degree) to the other age groups as well. For example, it was stated that teens respond well to a speaker who has established a positive relationship with them. This is especially true for teenagers, but it is also true (perhaps to a lesser extent) for the other age groups. Similarly, in the section on teaching adults it was stated that you should avoid berating your audience. This is also good advice for each age group.
And, perhaps most importantly, although I specifically mentioned storytelling in conjunction with teaching children, every age group loves to hear a well-told story. So become a storyteller!
In addition to the advice already given, there are a few last pointers I would like to offer.
Simple Vocabulary, Complex Ideas
You often hear people talk about "dumbing down," which is a term used to describe the process of teaching to the "lowest common denominator." I don't encourage "dumbing down" your lesson.
What I do encourage is this: keep your vocabulary simple with a mixed group, but that doesn't mean you should avoid complex ideas. In general, I look to my youngest group of listeners to help me gauge the level of vocabulary I should use, but I look to my oldest group of listeners to help me gauge the complexity of ideas I will deal with.
Why do I do this? By keeping the vocabulary simple, I guarantee that the youngest group will at least have a reasonable chance of following what I'm teaching. By focusing my ideas at the level of the older listeners, I am actually helping to expand the minds of the younger listeners. If I speak to them in terms and words they understand, they will catch glimpses of understanding of the ideas I'm teaching.
This has always been my mode of operation -- even when I'm doing ventriloquism, which many people regard as "kid stuff," I teach a lesson which is as much directed at the adults as the children. And it has always worked well for both the young and the old listeners.
Talk About Jesus
I don't mean simply saying the old tried-and-true phrases about Jesus: "Jesus saves," "Jesus loves you," "Jesus died for your sins." These are all true statements, but they are not really talking about Jesus -- they are simply repetitions of phrases your listeners have heard hundreds of times. Far too many teachers and preachers think that they have adequately taught about Jesus if they have repeated those phrases.
Really talk about Jesus. No matter what you are teaching, it should remind you of something Jesus said or did. A couple years ago I did a series of lessons on Proverbs 25, and in almost every verse I found myself saying, "This proverb makes me think of when Jesus said..." and off I would go on a story from the Gospels.
And here is what I have discovered: there is something about Jesus that really, truly appeals to every age group. You have heard the old saying: "When E. F. Hutton speaks, everyone listens." One might just as well say, "When Jesus speaks, everyone listens." People want to hear stories about Jesus, about His life and His death and His resurrection. They are hungry to hear these stories. And even if they've heard them before, they want to hear them again.
I love to tell the story of unseen things above,
Of Jesus and His glory, of Jesus and His love.
I love to tell the story because I know 'tis true,
It satisfies my longings as nothing else can do.
I love to tell the story -- 'tis pleasant to repeat
What seems, each time I tell it, more wonderfully sweet;
I love to tell the story, for some have never heard
The message of salvation from God's own holy Word.
I love to tell the story, for those who know it best
Seem hungering and thirsting to hear it like the rest;
And when in scenes of glory I sing the new, new song,
'Twill be the old, old story that I have loved so long.
I love to tell the story! 'Twill be my theme in glory
To tell the old, old story of Jesus and His love.