Should I Trust a Certificate
Trusting a certificate gives the owner of that certificate the ability to limit security warnings when performing some tasks. These tasks include installing new software, and intercepting &amp; proxying secure connections.

Whether you should follow the request to trust the certificate depends on who owns the computer.

See Should I let my child's school have access to my kid's personal laptop? for a related question over on the Information Security site.

School Device

If the computer is supplied by the school and the school want you to install their trusted certificate, then you should do so.

Personal Device

If this computer is yours, I would not trust their certificate. Adding an always trusted certificate is significant step and should rarely be needed on a personal device.

Minimum Trust

Note the sub-options in step 5:



You can choose to trust the certificate only for certain functions. If the certificate is intended to allow locally developed and signed software to run, then only Code Signing should be required. Maybe X.509 Basic Policy also.

I would avoid trusting Secure Sockets Layers (SSL) until it is proven essential. This trust would allow the school to intercept previously secure Internet connections.

You could incrementally trust/distrust parts the certificate until you found the minimum set of trust required.