Microbit via WebUSB on Ubuntu 18.04

Make sure you are running the latest firmware on the microbit

Create a new udev rule

sudo nano /etc/udev/rules.d/80-microbit.rules

With the following content

SUBSYSTEM=="usb", ATTR{idVendor}=="0d28", ATTR{idProduct}=="0204", MODE="0660", GROUP="plugdev"

Then if you want non-admin users to be able to use it (like your kids) run

sudo usermod -a -G plugdev non-admin-user

If you are admin you just need to unplug and replug the microbit (the udev rules run on hot-plug), if you are non-admin you will need to logout and back in to get the updated user groups

Then you can click on the Settings (top right) and click Pair device. After that you won't need to copy the files to the microbit, download will do everything need.