You cannot claim a deduction for money that you give directly to a teacher. In order to make a deductible contribution you have to give the money to the school, not to the teacher. The school has to be either a public school or a non-profit private school that is authorized by the IRS to accept tax-deductible donations, and you have to get a receipt from the school.

Charitable donations are an itemized deduction. The deduction will not reduce your tax unless your total itemized deductions are more than your standard deduction.