I believe that elementary aged students should be taught Bible stories. I think they should be immersed in Bible stories. They should hear them, see them, act them out, engage with them, review them, memorize them, be able to retell them. For six whole grades (six years), a children’s ministry should, on the formal level, immerse children in the stories of the Bible.
Bible stories don’t have to be taught in a chronological order, although I recommend it. After all, you typically don’t start the Lord of the Rings Trilogy in the climax of the second book, then jump to the opening plot twist of the third book, all the while referencing the “Fellowship of the Ring” that is created in the first book. It make sense to start at the beginning of the story and work your way to the end.
Granted, if you think in terms of C.S. Lewis who fashioned his Chronicles of Naria series, not in chronological order, rather intentionally jumping forward and backward with literary precision. There could be an intentionally creative intent by which a wise Christian educator could craft such an interesting weave of jumping in and out of stories in Scripture in order to create a marvelous tapestry of Biblical wonderment (cool sentence, huh?!).
All to say, that in my opinion, I think that from Kindergarten through grade 5 (loosely on either end), children should be immersed in the stories of the Bible.