Facebook is launching an educational tool as part of measures it is taking to counter fake news.

For three days, an ad will appear at the top of users' news feeds linking to advice on “how to spot fake news” and report it.

The campaign, which will be promoted in 14 countries, is “designed to help people become more discerning readers”, the social media firm said.
http://www.bbc.com/news/technology-39517033

Also see:

Facebook to offer users tips on spotting fake news
Hundreds of millions of Facebook users will be offered tips for spotting fake news as part of the social network’s latest attempt to address concerns about its role in the spread of false information.

The new “educational tool” is part of a multi-pronged strategy which will also see a growing range of “signals” from user behaviour and third-party fact checkers used to make misinformation less prominent on the social network.
https://www.theguardian.com/technology/2017/apr/06/facebook-to-offer-users-tips-on-spotting-fake-news