Yes, should click on one of the icons, or hover over it to display the menu and select the choice (only one) of Connect. But this is just the first step ........
If there is a lock symbol on the icon, she will need the "key" or "passphrase" (supplied by whoever owns the access point (icon)) that is then requested by a menu.
A different security protocol (WEP, WPA, WPA2) may be required at the school. There may be an additional password to pass through the school's internet router. The school access point must also only use wireless channels 1, 6, or 11 . This will be automatic on newer access points, but must be set on older ones.
It is unlikely the school has a "mesh" network. It will likely be a wireless like you have at home. The XO has its own "mesh" for working with another XO, but it can also connect to a home wireless (or school wireless) network.
These are things to ask the school --- if you can find the right knowledgeable person.
Sometimes, you need to clear out old network information using the Main Menu (under the X man) and Control Panel / Network / Delete network history , then reboot. Do not do this unless you know the keys / password phrase for your home wireless, which will have to be reentered.