The Initial Network Panel
In the Initial Network panel, you set the network from which the user will start the activity. One option for setting up the initial network is to simply copy from the answer network and edit parts of it. Do this by pressing the Show Initial Network button. Another option is to import a file using the Import File to Init Network button and to edit that file. After creating the initial network, you can export it using the Export Init Network to File button.
Using the Locking Tree
The tree in this mode is used to lock out functions to which you do not wish the student to have access. For example, you can prevent the student from switching to the Physical Workspace (under the Interface branch). The restrictions can be much more specific, such as preventing changes to the interface type on a specific port on a specific device (under the Topology --> Existing Devices branch). Be careful about what functions you lock because certain restrictions may prevent the student from finishing the activity.
The first screenshot above shows some appropriate items that should be locked for our simple example. This configuration takes away the student's ability to use Simulation Mode features. Without Simulation Mode, the student has to use the command prompt on a PC to send and diagnose pings.