Why don't you just make a normal lunch and eat half early and half late?

I'm assuming you have access to a fridge? My favorite snack-for-a-meal is hummus, pita, and some assorted veggies (cucumbers, red pepper, olives, tomatoes). You can just graze on it until you're full, or you can make veggie sandwiches in the pitas. If there's a toaster where you can warm the pita, even better.

I eat this way by choice, with my first meal being something like a yogurt smoothie or something like the photo (fruit and peanut butter) and the second usually being a salad (hearty with beans, buts, or cheese added), a pasta, or a soup. Your needs will dictate whether you prefer the heartier meal to be first or second. Eating two halves of the same meal would get boring to me, and making one more of a snack (but include protein or whole grain to make it last) works well.

Hummus and carrots, peanut butter and apples, cheese cubes or string cheese, granola, plain Greek yogurt with honey and walnuts, banana bread with peanut or almond butter, rice or whole wheat crackers...etc. And I agree with the above comment - you could always make a whole sandwich, wrap, or salad and eat half early and half later.

Customized Granola Bars! Much healthier than store bought as well.
Here's the link.

http://movesfast.blogspot.ca/2012/08/customize-your-granola-bar.html

I don't think it's that Kitchn readers "can't figure it out." It's helpful to get even simple ideas for things we do everyday. I'll never get tired of healthy snack ideas.

Teaching is draining, so make sure you're consuming enough calories (protein and fat, especially). Hummus, cheese, tortilla, salami, smoked salmon, pâté, nuts (if allowed in school), with a variety of veg, fresh herbs, and fruit.

I transitioned to teaching from business and one of the hardest things to acclimate to is the quick and early lunch. My running favorites include a toasted waffle with peanut butter and a half a banana, healthy crackers with ricotta or goat cheese and a bit of jelly or "savory" greek yogurt with a mixture of seeds, nuts and dried cranberries or cherries.

I second @welcomereality. My wife is a teacher with a late lunch period and a mid-morning prep, and she always eats half of her lunch during prep and the other half during lunch.

I eat this way by choice too. For the early lunch, I would do something breakfast-ish like crustless quiche (egg and vegetable baked on the weekend and squares cut all week for this meal).

Good luck on your first year of teaching! I come from a family of teachers so I know how exhausting the first year is...

Anyway, if it were me I would pack an entree (say, a sandwich) and some fruit and veggie sides. Then I would eat the fruits and veggies first to make sure I got them in for the day! Then I would eat the entree later.

This may or may not help, but my midmorning snack is usually something easy to grab like cherry tomatoes, pomegranate seeds, cherries, babybel or polenguinho cheese.
You could thread cubes of fruits, veggies &cheese onto small skewers that are easy to snack on.
Bento recipes might work well, since there are tons of great ideas and its easy to split lunch into phases. One site I like is, http://justbento.com/

I'm also a teacher who usually has an early lunch and I'm always trying to improve my meal plans and snacks. One thing I can recommend having around is a big box of frosted shredded wheat. I take a handful for a snack whenever I need it. I like that it satisfies my craving for junk, but it isn't terrible for you. And when you're wiped out, you don't feel like making fancy snacks, so it's convenient.

I agree with the recommendation to split your lunch in half but also add some snacks such as apples and almonds. Good luck in your first year teaching!!