National STEM Education Tax Incentive for Teachers Act of 2011 - Amends the Internal Revenue Code to allow certain full-time elementary and secondary school teachers of mathematics, science, engineering, or technology courses a refundable tax credit for 10% of their undergraduate tuition up to $1,000 in any taxable year, limited to a 10-year period. Increases such credit amount to $1,500 for teachers in schools serving disadvantaged children.