The main field method is deliberately simple.
computer -> quality USB stickThis avoids depending on internet, cloud accounts, Bluetooth pairing, or complicated installation steps at the destination.
Do not use the cheapest unknown stick for field delivery. A bad stick can fail, corrupt files, or disappear into confusion.
The stick carries the learning. Treat it like the master copy.
Do not copy only the images. Do not copy only the HTML. Copy the whole folder.
Carry two copies when possible.
If the working stick is lost or damaged, the master stick still protects the content.
Two small sticks can protect the whole trip.
Android is the recommended field device because local files, USB sticks, SD cards, and folder copying are usually easier to manage.
If another phone needs a copy, use the easiest local method available.
If a folder cannot be sent directly, compress the folder into a ZIP file, send the ZIP, then extract it on the other phone.
Updates do not require a new phone.
Replace the whole folder. Do not mix old and new files.
The system does not have to be perfect. It has to be understandable, repeatable, and useful where children are.
The phone is the viewing device. The USB stick is the carrier. The folder is the learning package.
Carry knowledge on a stick. Load it into a phone. Leave learning behind.