How a 1993 plan to launch ads into space turned into a national freakout. In the 1990s, space was for sale. Breakthroughs, discoveries, and DIY tips sent every weekday. In 1993, Mike Lawson, an aerospace entrepreneur based in Roswell, Georgia, unveiled his vision for a brave new future of advertising: space billboards. This wasn't a half-baked scheme: Lawson had meticulous plans for a proposed 1996 launch: His team of engineers would shoot a package of tightly-wound mylar into orbit about 180 miles above the Earth.

As these teachers have come to understand, you don't have to be technically minded to introduce your students to the important concepts behind artificial intelligence. When computer science teacher Sharon Harrison wanted to introduce her eighth graders to the basic idea of artificial intelligence, she had them try out an online chatbot called Akinator, which asks the user questions to determine what historic or fictional character he or she is thinking of. In some instances, the students marveled at how quickly the program could figure out the answer. "Sometimes it would guess in three or four guesses, and we'd say, 'How on earth was it able to do that?'" From there, the discussion in this elective class at the University of Chicago Laboratory Schools examined how responses to the chatbot could be sabotaged -- by responding to the questions incorrectly, and thereby "damage the integrity of the program."

JUDY WOODRUFF: Now we continue our special series on Rethinking College with a look at graduate students who pay little or even nothing for a top 10 master's degree program. HARI SREENIVASAN: It's graduation day, and these two students are earning their computer science master's degree from a top 10 program in the country. But it's the first time they have ever visited campus. VANESSA ANDERSON, Graduate: This whole experience was very surreal. This is my first time on campus, being here.