Maybe you can create sub-domains for your students.
For example,
1) your site: http://rootdomain.com
2) student1: http://student1.rootdomain.com
3) student2: http://student2.rootdomain.com
4) student3: http://student3.rootdoamin.com
.
.
. etc
Then install WordPress individually into the sub domains. It takes time, but it fits your requirements of privacy.
Alternatively, you can also use folders instead of sub domains.
Multisite. Which is what firebladex suggested, but a lot less work.
http://codex.wordpress.org/Create_A_Network
What are privacy requirements, exactly. Are students not to have access to other student blogs?
Has Multisite setup been decided upon? Plugin “Registered Users Only” allows only registered users to view a standard WordPress.org installation and site, but users can view other students work.
Do you want all to employ the same theme, or have options to design their own? This option might distract from the photography evaluations and make it more difficult to observe the work due to having to learn different theme structures.
In a standard wp org site, students each could have a Subcategory of their name or alias under a Student category, while the Multisite option could allow a separation between users.
Another plugin called “Private Files” might be useful.
http://wordpress.org/extend/plugins/registered-users-only/
http://wordpress.org/extend/plugins/private-files/
