Your materials will leak. What to do about it.

Every tutor who builds good material eventually finds it circulating: in a group they do not run, under someone else's name, or free on a channel with thousands of members. The instinct is to lock everything down. It is worth being clear about which locks work.

The uncomfortable baseline

Anything a student can see, a student can photograph. Watermarks, disabled downloads and screenshot blocking can all be defeated by a second phone pointed at a screen, and none of them survive a determined teenager. Any strategy whose premise is "they will not be able to copy it" is built on something false.

What actually reduces leaking

• Per-student watermarking. It does not prevent copying; it makes the copier identifiable. That changes behaviour far more than a lock does, because the risk shifts onto the person sharing.
• Time-limited links rather than files. A link that expires cannot be forwarded usefully a month later. Most casual sharing is lazy, and expiry defeats lazy.
• Not sending the answer key with the sheet. The key is what makes leaked material valuable to a stranger. Released separately and later, the sheet alone is worth much less.
• Saying it once, clearly. A short, calm statement that materials are for the group produces a real reduction, because most sharing is thoughtless rather than hostile.

What is not worth your time

Elaborate DRM, chasing every leak, and threatening groups of teenagers. The hours cost more than the leak, and enforcement against your own paying students damages the thing that actually earns your income.

Protect the part that cannot be copied

The strategic answer is that your PDF is not your product. A stranger with your worksheet does not have your explanation, your marking, your knowledge of that student, or the exam analysis you give in the session. Tutors whose whole offering is a document are genuinely vulnerable; tutors whose document is the artefact of a service are much less so.

This is also a reason to make the session, not the file, the thing worth paying for. A leaked sheet then advertises you instead of replacing you.

Sources

• UNESCO — Education
• International Labour Organization — Teachers and education personnel