Read A(n) historical take on the evolving use of a/an (The Christian Science Monitor)
English speakers disagree – sometimes vehemently – about how to use “historic” and “historical” with the indefinite articles a/an.
Went down the rabbit hole a bit on this topic this afternoon. Also spent several minutes reading the couple of pages that Fowler’s has on the topic. 
 
Mostly looking at the idea of whether it should be a Hispanic or an Hispanic.
Read a post by Miraz Jordan (miraz.me)
Informing yourself about the aftermath of recent events? Did you know that the ‘math’ part originally referred to mowing a field? The “aftermath” is the new growth that comes after said field or meadow is mowed. Recommended podcast, by the way — a 5 minute listen each week. Screenshot from...
Watched Breaking the language barrier | Tim Doner | TEDxTeen 2014 from YouTube

Tim Doner is a senior at the Dalton School in New York City who has studied over 20 languages. His interest started at the age of 13, after several years of French and Latin, when he began learning Hebrew and soon moved on to more obscure tongues such as Pashto, Ojibwe and Swahili. As he describes it, his goal is not to achieve fluency in each, but rather to learn about foreign history and culture through the medium of language. He spends much of his time perfecting his linguistic skills in different neighborhoods around the city, and to date his Youtube channel has received over 3 million hits. Tim has been interviewed (in English, Mandarin, Arabic and Farsi, among others) for media outlets such as The New York Times, BBC, The Today Show, Reuters and The Economist. He is starting his freshman year at Harvard next year and plans to study linguistics.

A nice hook to pull one into some of the reasons why one would want to pick up languages as well as how to do so.

8:44 method of loci (locorum)

10:02 Learning words in groups based on related sounds.

11:22 Why learn languages? Some useful motivation here.

Language represents a world cultural view. This is particularly poignant because a language (and its methods of thinking, viewing the world, and usually lots of associated culture) disappears from the world every two weeks.

Read Merriam-Webster changes its definition of 'sexual preference' as Barrett gets called out for using term (Fox News)
Merriam-Webster dictionary changed its definition of “sexual preference” to include the word “offensive” as Democrats slammed Supreme Court nominee Judge Amy Coney Barrett for using the term during Tuesday’s Senate confirmation hearings.
Interesting to see historical linguistics playing out in real time in the news apparently.
Read What's Next? Scots, Scottish Gaelic, and the Scottish Identity by Melissa Puthenmadom (eucenterillinois-language.blogspot.com)
With the Scottish independence referendum looming over the horizon—scheduled to take place on September 18, 2014—the presence of Scotland’s regional and minority languages has become more relevant than ever. Today, the only official language in Scotland is English, while Scottish Gaelic and Scots are recognized as regional languages. You might ask: what’s the difference?
Read Language in England and Wales - Office for National Statistics (ons.gov.uk)
Using data from the 2011 Census, we take a closer look at language within England and Wales. Those who reported English (or Welsh in Wales) as their main language accounted for 92.3% of the population, except in London where proportion was much lower. Those who reported another main language accounted for 7.7% of the population, with Polish topping the list of "other" main languages. London and the West Midlands saw the highest percentage of people who could not speak English "well" or "at all".
Read Most Spoken Languages (most-spoken-languages.sanstream.nl | SanStream Studio)
When we are young we first learn the language from the people around us. This helps us to communicate, share ideas and learn from them. Most of the time just this is just one, but it can be more than one. The last decades the network of people that human being know (due to globalisation) has shifted from knowing just the people in your local area to people all across the world. In order to effectively communicate with other people from across the world it is useful to speak a shared language.

Finding data 

You’re right about data here. I follow some research out of the MIT Media lab by Cesar Hidalgo who may have some interesting data resources if you poke around.

Some additional starting points:

Read UK accused of failing to promote minority languages by Severin Carrell (the Guardian)
Critical report by Council of Europe calls for more support for Cornish, Irish and Ulster Scots
The benefits of speaking multiple languages are fairly well documented. How can we–as a society–better support additional languages? Why are we constantly sidelining and devaluing people’s mother tongues? 
Watched How to learn any language in six months by Chris Lonsdale from TEDxLingnanUniversity | YouTube
Chris Lonsdale is Managing Director of Chris Lonsdale & Associates, a company established to catalyse breakthrough performance for individuals and senior teams. In addition, he has also developed a unique and integrated approach to learning that gives people the means to acquire language or complex technical knowledge in short periods of time.
Attention, meaning, relevance and memory

Five Principles

  1. Focus on language content that is relevant to you (We learn tools fastest when they are relevant to us)
  2. Use your language as a tool to communicate from day 1
  3. When you first understand the message you will unconsciously acquire the language (Krashen ,2013)
  4. physiological training
  5. Psycho-physiological state matters, learn when happy and don’t get frustrated

7 actions for rapid language acquisition

  1.  Listen a lot (brain soaking)
  2. Focus on getting the meaning first (use body language)
  3. Start mixing and be creative
  4.  focus on the core
    1. Week 1: The Tool box (learn to say the following all in the target language)
      * What is this
      * How do you say?
      * I don’t understand
    2. Week 2-3 pronouns, common adverbs, adjectives
    3. Week 4 glue words, but and, though
  5. Get a language parent to help you understand
    1. works to understand what you are saying
    2. does not correct mistakes
    3. confirms understanding by using correct language
    4. uses words the learner knows
  6. Copy the face
    1. Work on the muscles and look at native speakers
  7. Direct connect to mental image (visual association)
Watched Gaelscoilis -- error-laden pidgin or creative creole by Breandan mac Ardghail from TEDxFulbrightDublin | YouTube
Breandán Mac Ardghail's talk is entitled Gaelscoilis: An error-laden pidgin or a deviously creative creole? By exploring the weird and wonderful linguistic features of the language spoken in Irish immersion schools, he offers an alternative perspective on the non-native schoolyard Irish of Gaelscoil pupils. In 2012, Breandán was a Fulbright Foreign Language Teaching Assistant at the University of Montana.