I would recommend getting a laptop that the function USB-C PD - this allows you to sidestep the issue of the laptop battery by having a plugged in power source such as high wattage powerbanks to properly feed the laptop while sitting in the classroom. You dont need a cord to reach the outlet but something to go into your backpack and feed from there.

Best examples:

https://www.amazon.com/POIYTL-20000mAh-Portable-Charging-External/dp/B0B4W3Z62N/ref

or https://www.amazon.com/DEWALT-USB-CHARGING-KIT-DCB094K/dp/B09YY1WTHJ

and external batteries: https://www.amazon.com/gp/product/B07XHFFP74/

The first one is a basic powerbank while item 2 and 3 becomes a modular battery pack allowing you to have additional 1.25 to 1.5X battery life while connected to the USB-C PD cord. Granted its adding another 3 lbs to your pack but it allows you to function without need to provide power. However recharging could be better off with a high end multiple USB-C charging bank such as https://www.amazon.com/Charger-HUNDA-Portable-Charging-Station/dp/B0BMG53J1V/ref

This is a 5 port (3 USB C) charger at 245W allowing you to charge 3 large wattage devices quickly.

Is your tool battery dewalt? They have a 100w USB-C PD adapter for the batteries that allow for two way charging now