Around here, school starts on Wednesday.
Since this is a practical survivalist group, let's talk about what parents of schoolchildren can do.
I don't encourage loading up a backpack until it causes permanent damage for the child carrying it, but there are some things parents might want to consider stashing in one.
A granola bar. Homemade is tastier and better and cheaper, but store bought works, too. Even if it gets all smashed up, it's still edible, and they will eat it if they have to skip lunch or need a snack between school and some after school activity. Check the pack daily and when they eat it, replace it.
A small, flat flashlight (LED is good) that can hang on the key fob in their backpack. Check it for batteries once in a while. They can use it during black-outs, to see the lock to guide in the key in the winter when it gets dark so early, in case they get locked into a dark room or locker, or to find something the fell on the floor in a darkened part of the room.
Immunization record. I'd laminate it and slide it into the back of a pocket. The school should already have a copy, but it's not the school's responsibility to keep that record or to include it in any transcripts. The immunization record is part of their medical history and therefore the best place to go to get duplicates of the immunization records is the doctor's office. Some doctors don't keep track of immunizations (I have no idea why not), and with the school not obligated to keep track, either, a copy hidden in the back pack is a good idea - you'll always rememebr where to look for it when it's needed.
USB drive with essential information on it: scanned copy of their passport, medical information, contact information, photos.
Freezer packs in their lunch kit inside their back pack (or hanging off it) to keep to safe and edible. Cold and hot foods should be kept separated, with the cold foods on the bottom and the hot foods above a separation panel.
$10 or $20 hidden inside a hidden pocket in their back pack. This way, if they call saying they need money for lunch or school photos or something, they'll already have the money with them and all you have to do is direct them to it - no taking off work and driving to school to give them the money.
Tiny plastic poncho because you never know when they might need it for rain or impulsive science experiments.
An info card. Cell phones can be lost or damaged, so having essential contact information available in a more primitive format is essential. Put on it such things as their name, address, parent's contact info, classroom number, bus number, any allergies, medications, or medical problems, a copy of the family emergency plan, a map to the emergency meeting location, etc. This is also on the USB drive mentioned above, but USB drives can be lost or rendered unreadable. A 3x5 card with this information on it, tucked into a plastic card holder in the back pack could save your child's life in an emergency.
Appropriate safety gear: a helmet if they ride their bike to work, a jacket or vest with reflective stripes on it, a bicycle repair manual (the kit should be on the bike), a small first aid kit (bandaids, antibiotic cream, handwashing soap leaves or germ-x), etc.
Emergency meds (like epi-pens and inhalers). Some schools have restrictions on these, so check with the school, but if your child's allergy is so severe they can't wait for help to arrive, make sure they at least have the epi-pen.
In addition to those small items, also make sure your child has skills: knows how to do a Heimlich Maneuver properly, knows how to do CPR, how to call and talk to 911, how to resist peer pressure, basic self-defense skills, what to do if a stranger approaches them, when to run away, when to scream, etc. Don't try to scare the kids, present these skills as benchmarks of trustworthiness. The better they master taking care of themselves, the more trust you place in their judgement and the more freedom they earn.
Last, but not least:
Emergency Cell phone. Program in emergency contact information - you (obviously), doctor (and label the names with the relationship - a lot of EMTs now search cell phones for that information and it speeds up the search if MOM, DAD, DOCTOR, etc are labeled as such instead of having to call each number to see who they are), grandparents, siblings, aunts, uncles, trusted neighbors, etc. If it's a pay-as-you-go phone, I wouldn't let them give out the number to their friends - it's a "911" cell phone for emergency use only - and you determine the emergency (I limited to the "B"S: Broken, Bleeding, Burning, you can use whatever criteria you choose). If it's a smartphone and they are on the family plan, set whatever limits you want on the phone use. If it's a smart phone or tablet, there are plenty of apps that could come in handy during an emergency. Some are free, some cost. They include hurricane and tornado warnings, bus schedules, and so on. Sit down with your children and go through these apps. Download the ones you think might be useful. They may never need them, but since it's available and lightweight - why not?
I'm sure there's more you can think of that might be appropriate to your particular situation. Maybe you think more is needed, or less, but do consider what your child might need during their day and teach them to make their own personalized survival kit.
Please note I did not include some of the typical "survivalist" gear - no fishing hooks, pocket knives, pocket saws, or anything of that sort. Mostly it's a bit of money, contact information, flashlight, bandaids, snacks. I'd include a refillable bottle for water, and if no cell phone, maybe a digital camera.