Of course, with either the biographical or historical serial plan, great pains must be taken with that bugbear of the average teacher,—what the lesson-helps call intervening events, but many a scholar calls intervening mystifications. Often fully half the lesson-time should be given to them. Usually the antecedents they contain are absolutely necessary for an understanding of the lesson,—text, persons, and principles. With them you teach history; without, episodes. They mean work, to be sure; but all unifying and solidifying means work.
At still other times or with other classes it is well to let the serial interest center around principles. Treat one group of lessons as illustrating the manly or unmanly qualities; consider another group primarily as a commentary on truth and falsehood; let your binding topic for another set be "What is True Religion?" "Sin and Salvation," "Serving and Served," "Success and Failure,"—how many lessons could be clustered naturally about these topics! Children are characteristically philosophers, and a treatment of Sunday-school lessons as illustrating different phases of some great truth is a method very attractive to them. "What does the Bible teach about truth-telling, about penalty for sin, about the conditions of happiness?" Sunday-school scholars should be ready to answer such questions, not by haphazard impromptus, but by a careful presentation of events, characters, and sayings bearing on each point, and representing the whole Bible.
Another excellent way of binding lessons together is by the scholars themselves. As I said, however the lessons change, the scholars remain the same, with the same prominent troubles, faults, and needs. Both they and you should know what these are. I often have scholars who bring up, Sunday after Sunday, in connection with topics the most diverse, the same questions, which are evidently stumbling-blocks to their minds and lives. These are usually practical matters wherein the Christian imperatives are strangely incongruous with worldly habits, such as the choice of a calling, absolute frankness of speech, public testimony for Christ, the careful observance of the Sabbath, sharp competition in trade. These are too big questions to be settled in a few minutes, and young folks who are seized by them in earnest have found for themselves a serial interest which will last for some time.
If we cannot take advantage of such a linking which our scholars discover for themselves, we can always bind lessons together by our own knowledge of our scholars' needs. If you have a young man in your class to whom the skepticism of the times is alluring, let him find something faith-inspiring and confirmatory of belief in every lesson. If you have a young girl burdened with sick-room duties and home cares beyond her strength, let her know that each lesson will bring her fresh energy and comfort. You need not tell your scholars that you know their struggles. Enough that you do know them, and link lesson to lesson for them in sweet chains of love and helpfulness.
When, by any of the four methods I have outlined, you thus establish a bond between your lessons, you have gained two great advantages besides the serial interest which you have aroused. In the first place, you study the Bible as a whole, not by extracts. You learn to interpret one portion by another. You find out the fallacy of fragments. You perceive that Christianity is a system, and not an anthology. In the second place, you have solved the review problem, for every lesson is now a review. If you were required to remember, in order, twelve words chosen at random, you would find it somewhat difficult; but it would be easy enough if those twelve words were arranged in a sentence. Serial teaching is building up a sentence, and the review is merely repeating that sentence. A serial teacher has no fear of review day. The short-story teacher is compelled to find for that day a new short story.
Now, have I not reserved mention of the one great tie of all our teaching? Whether Old Testament or New, history, prophecy, proverbs, or psalms, it is all one continued story, and the hero is Christ. By whatever unifying principle we group our lessons together, Christ unifies the groups. Year in, year out, if Christ is at the heart of our teaching, that teaching is consecutive, serial, solid. Without him, it is disjointed, fragmentary, frail. Not retracting a word I have written about the value of these other methods of arousing continued interest, yet it must be said that they are all worthless without Christ. In him each several building, fitly framed together, groweth into a holy temple in the Lord.