Prosecutors dropped an aggravated assault charge in exchange for the boy's guilty plea to a charge of tampering with a food product.
Authorities say the victim sipped the soda, then spit it out as his classmates laughed on March 29.
A judge ordered the boy to serve probation, serve 200 hours of community service, write a letter to the victim to apologize - and to write a 1,000-word report on why it's unhealthy to ingest fecal matter.