The following steps will reconfigure your existing Wi-Fi setting and Launch the network experience from scratch.
1. Turn WIFI off and close out all browsers and applications.
2. Go to the apple menu on the top left hand corner and select Go.
3. Select " Go to Folder"
3. Paste in the following line: /Library/Preferences/SystemConfiguration/
4. Select the files listed below ( as shown on the screenshot) and Delete them (move to trash)
5. Once you have deleted those files restart your device and log back in. You will need to select the GCISD-WIRELESS network and it will prompt you to type in your GCISD credentials.
That should re authenticate you back on the GCISD-WIRELESS network and you should be connected to wifi once again.