. >> ifill: john tulenko of learning matters reports on tennessee's plan to reward teachers when students do well. >> we need to move to a system that says if you work harder, if you do better, if you try to improve your craft and your students perform better, you get paid more. >> lehrer: we have an election season look at campaign cash-- who's giving, and why. >> ifill: margaret warner examines the impact international sanctions are having on iranians. >> they're having a dramatic impact. i think that the u.n. security council resolution was underestimated . it was underestimated by iran and it was undersfimented by lots of people in the international community. >> lehrer: that's all ahead on tonight's newshour. major funding for the pbs newshour has been provided by: and with the ongoing support of these institutions and foundations. and... this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> lehrer: today's vote in the u.s. senate means the ban on gays in the military will stand, at lea