Facebook is in the news this week, for handing over 3,000 Russian-linked ads to congressional investigators. Unlike ads for politicians or causes that appear in print, TV or on the radio, Facebook ads are not fact checked, and it’s often not clear who paid for them. A new tool from news organization ProPublica aims to make this information more transparent. For more, Lizzie O’Leary spoke with ProPublica senior reporter, Julia Angwin.