Here's me teaching with with C-SPAN.
The 7th grade is doing a short unit on the expansion of slavery, starting with the Missouri Compromise. To help us better understand slavery, we are reading Narrative of the Life of Frederick Douglass - an American Slave, Written by Himself.
In the video of me teaching you will see me explain the crisis that is created when Missouri wants to join the Union, threatening to upset the perfect balance of 11 Free states and 11 Slave states. The kids come up with some possible solutions (including the real one - to add one of each to maintain balance) and we talk about the 36-30 line. Then we discuss what should/would happen if a slave is brought above the 36-30 line, into free states/territories.
This actually happened quite often obviously, but in the 1850s one slave, Dred Scott, sued for his freedom, saying that once he was brought north he was free. The case went all the way to the Supreme Court. In the C-SPAN video, we see Harold Holzer (who was in the NYT this week, I think, discussing how black men get a raw deal in America even while the programs that exist to help other minority groups are actually working) discussing the importance of the Dred Scott case and the results of the Supreme Court decision.