I have re-read my very, very bookmarked and bent copy of the Craft, but have not been able to find Stephen King's insights into the problem of how to handle multiple ideas? I've been working on one novel (also while teacher high school, but History, and college) and keep finding fantastic, at least to me, ideas for stories. I outline my plan (sorry Stephen) while working on my current novel. How does everyone handle this dilemma of too many ideas? I keep a journal of ideas, but find that the stories intertwine in my mind while trying to work on a single story. Do most focus only on one novel at a time or has anyone tried multiple writing projects? Thanks!
I'd say you need to find a system that works for you, and not worry about what works for SK or other writers. If you can work on more than one story at a time without becoming confused or losing pace then go for it. If not, though, then continue to make notes/plans so you don't forget your ideas. You say the stories intertwine in your mind...is there a possibility that these stories could become sub-plots in the novel you're working on? Just a suggestion.
If I only had one story going on at a time, I would think something is wrong with me. Currently, I'm working on my second novel with several short stories bouncing around in the background. Whenever I feel like I need a break from the novel, I work on one of the shorts. If I have an idea for a new novel, I'll write a couple pages of it and/or a basic outline and then it has to wait until I'm done with the current novel. I would never try to get deep into more than one novel at a time, but that's just me.
I'd say if you follow every idea "through" to the end of your proposed story, you may find that most of them are bunk. The better ideas will hold their own as you craft the "rest of the story..." - that's just my take. I get many ideas too, but most are bunk if I try to develop them beyond being an idea.
I've found sometimes, you actually have to filter them out before they get to the page. I'm a hybrid of discovery, and outliner. So sometimes I might have a really good dream, decides to write down the core idea, and jot this down.