American School Systems

OK here is a simple version of the ages and the relevant grades of the American school system:

• Kindergarten 5-6
• 1st Grade 6-7
• 2nd Grade 7-8
• 3rd Grade 8-9 
• 4th Grade 9-10
• 5th Grade 10-11
• 6th Grade 11-12
• 7th Grade 12-13
• 8th Grade 13-14
• 9th Grade 14-15  (Freshman)
• 10th Grade 15-16 (Sophomore)
• 11th Grade 16-17 (Junior)
• 12th Grade 17-18 (Senior) 

This is the general view of the system for those of us who aren't overly familiar with the American system and will hopefully clarify what they are on about in American movies.