Can Teachers make a Gradebook not visible to Parents?

In Portal Options, under the Gradebook tab, enable the option Allow Teachers to Hide Gradebooks from Parents and Students 

An option will then become available to teachers in their Gradebooks under the Manage Options tab. The Hide this gradebook from Parents and Students option defaults to disabled. It can be enabled or disabled in each Gradebook. If it is enabled, the Gradebook will not show in the Student or Parent Portals.