The HS will send transcripts that record your grades "to date". That is to say that the colleges/universities will look at your grades through the end of 11th grade, and whatever mid-term or mid-year grades you have so far for this year. After the school year ends and you have your final grades for 12th grade, you HS will send a copy of your final transcript to the college/university that has accepted you and that you plan to attend. If you slack off between now and the end of the year, and if your final grades aren't as good as the college/university that has accepted you expected, you might have your admission rescinded. This happens to students every single year, so keep working until the very end!