Well, SSI means you are disabled and don't have much money. You have to tread this carefully because if you're disabled, can you work if you can go to school? Search the internet. Here's part of the answer from disabilitysecrets.com .
The Social Security Administration (SSA) has no prohibition restricting a person who is receiving Social Security disability insurance (SSDI) or Supplemental Security Income (SSI) benefits from taking classes, full or part time.
However, your case is reviewed by the SSA from time to time to see if your condition has improved, and going to school full time could reflect on whether you are still totally disabled, especially if you were approved for disability benefits on the basis of a mental impairment (such as depression, bipolar disorder, or a cognitive deficit). If this is the case, you may find it best not to broadcast the fact that you're going to school full time when your case is re-evaluated at a continuing disability review, or CDR.
A disability examiner reviewing the case might leap to the conclusion that the recipient no longer meets the definition of disability. Of course, this may not be true at all, especially in the case of a mental impairment that becomes exacerbated and then improves. For the individual who is mentally impaired, this fluctuation is often a response to environmental stressors. Having to conform to the day-in, day-out requirements of substantial gainful employment can certainly expose an individual to such stress demands. By contrast, the requirements of attending school are usually not nearly so demanding or stressful.