I view my RAW photos from my Canon 550D on my home PC using Canon Zoom Browser. If I transfer them to a USB stick I cannot read them on another PC when I am at my Photoshop CS5 class.
The original version of Photoshop CS5 (which uses Adobe Camera Raw version 6.0) did not support the Canon 550D. Adobe later released Camera Raw version 6.1 which does include support for the 550D and which is also compatible with CS5. The last version of Adobe camera Raw that works with CS5 is version 6.7.
Ask the owner of the PC at your classes if they can update the version of Adobe Camera Raw used by Photoshop CS5 to version 6.7. It is a free download from Adobe.
Use the Adobe DNG Converter to convert your Canon Raw files to Adobe's Digital Negative (DNG) format.