Today's coverage centers on the U.S. Constitution: We have a quiz, a bit of history on the document, and some true-or-false trivia about the original signers. And as Americans prepare for the exercise outlined in Article II, Section 1, we're following a pair of TikTokers -- one on the political left and one on the political right -- to see how they're trying to influence voters through social media. Also featured: a report on how litter changed a cave's environment and a look at the world's wackiest car collection.