Of all the lessons I've learned giving two lectures a week, the most important is how long the prep takes - way more time than I ever thought possible. In undergrad, I was pretty sure that it took about as long to prep a lecture as to give one, if that. And in some cases, that may have been correct - lecturers who have been at it for ages and a day have a wealth of lectures and knowledge to draw on, and probably don't need to put in the sort of hours a new lecturer does. Also, some of them just don't bother - and it shows.
But, from my experience, if you're creating the lecture from scratch, from reading to finalising the materials, you're looking at about ~25 hours of prep for a 1 hour lecture. That may seem crazy, and it might be, I may well be underestimating. But to give you a breakdown of how it works for me...
~10-15 hours of reading. For me, it's about a text a lecture, perhaps 150 pages or so, plus the secondary source reading necessary to give students a full grasp of the topic
~ 5 hours of note-taking. I always underline when I read (pencil, not pen, I have commitment issues) and then take down the notes on my laptop afterwards. It's at this stage that it typically becomes clear what the main headings are going to be - the themes that need addressing.
~ 3 hours of lecture writing. From the notes, I write out the structure and content of the lecture. I like to structure my lecture like the notes I'm hoping the students take. I don't write out a script - I encourage students to interrupt with questions, and a script isn't flexible enough for this. Instead, it's very detailed bullet point notes. There's a lot of going back to secondary sources here too.
~ 1 hour of material prep. Handouts and powerpoints. I use handouts for quotations, and finicky dates and names (that way students are overly-stressed about getting those down during the lecture) and powerpoints for images and ideas that they can latch on to. Sometimes a name, an event, becomes more memorable if there's a mental image associated with it. I also like to show film clips and use music if that's applicable too. Finally, I use powerpoints for concept-mapping and when ideas are best expressed visually. Students learn in different ways, and can adopt a lot of these techniques in their own revision.
~ 2 hours cue cards. I always write my lectures down on cue cards. This is a final chance to cut out superfluous information (because you're eager to cut stuff out when you have to write it by hand on itty-bitty cue cards), finalise structure, and get it a little memorised, allowing you to be more engaged when actually giving the lecture. I always leave this bit for a few days before, even if I've done the other stuff weeks in advance.
And, when it takes this long, you do want to be doing it weeks in advance if you can. Because if you've got 2 hours of lecture a week, that's 50 hours prep, before there's any marking, office hours, tutorials, emails, bureaucracy or research of your own (ok... that last one was a joke). No surprise then than EC academics can be pulling 60+ hour weeks.
This is just my process, and it'll be personal for everyone, but the more I talk to colleagues, the more that this 25 hours seems close to the magic number. I'd really like to hear from others on it, however. What's your process? How much time does it take you?
I love teaching, and I love lecturing. I am glad, however, that someone shared with me how long the whole process took long in advance, so it didn't come as a surprise.