What do I do with how I am paid? annual salary versus daily rate?

I started working for a school district in January which is, of course, the middle of the school year. I was quoted an annual salary that was to be spread out over 12 months (I am an 11 month, 220 day employee). However, when my gross monthly salary is multiplied by 12, it equals an annual salary nearly $4,000 a year less than what I was quoted.

When I approached this issue, I was told how they figured my daily rate and then multiplied that by the number of days remaining in the contract and then divided that amount by the number of paychecks to be received before the next contract period. For example:

If I'm told 12,000 a year spread of 12 months, then that equals 1,000 per month. However, they get the daily rate--12,000 divided by 220 = 54.55--and multiply that by the number of days remaining in the contract--Jan10 to end of June = 117 days; 54.55 x 117 = 6382.35--and then divide that amount by the number of checks to receive--7 checks (Jan-Jul) ... 911.76 per month, not 1000. ??