As the son of two English teachers growing up in the late 1970s, I was introduced early on to the tale that teaching is one of the more underappreciated and underpaid professions on the planet.

But if LinkedIn's $1.5 billion acquisition of e-learning website Lynda.com in 2015 is any indication, times have changed.

In the 21st century, teaching sells.

And that's the secret behind the largest acquisition in the history of LinkedIn, which boasts 400 million members in 200 countries and adds two new members every second.

Why LinkedIn is betting big on online learning.

The world's largest professionally themed social network has a very specific vision -- one where every professional on the planet visits LinkedIn to not only network or look for a job, but to also consume content related to his or her industry and to learn how to do his or her job better through on-demand, e-learning courses spanning every profession imaginable.

To put this into perspective, consider that in 2011, about $35.6 billion was spent on self-paced e-learning worldwide. In 2014, e-learning was a $56.2 billion industry, and that number hit $107 billion in 2015.

That's why LinkedIn spent more than three times what it had paid for all of its previous acquisitions combined(!) in acquiring online learning site Lynda.com for $1.5 billion.

How you can sell more by "teaching" on LinkedIn.

With all that said, it's time to explore the impact on those of us wanting to use LinkedIn to generate sales leads, add clients, and increase revenue.

First off, the practice of Content Marketing (attracting your ideal customer or client by first sharing valuable free advice, information or tips online) is no longer optional.

It's required.

Here's why: Every sales person since the dawn of time has heard this caveat: Clients and customers want to do business with people they know, like, and trust.

When done well, Content Marketing items like blog posts, white papers, training videos, webinars, and e-learning courses are the perfect way to achieve all three requirements.

For instance, a great piece of free content not only demonstrates your expertise to a targeted audience in a specific niche or industry, but it can also make you likable -- especially if you inject some personality into your content and use tools like video on your LinkedIn profile and posts to showcase your personality.

Your golden opportunity: Leverage LinkedIn's massive B2B platform.

Here's the thing: LinkedIn wants to be the hub for every piece of professionally themed content you create.

The site has given its 400 million members our own blogging platform, and LinkedIn now curates and aggregates the best posts into themed news channels, often featuring top-shelf, member-created content on its main "Pulse" news feeds.

It won't be long before you and I can even submit online training courses, webinars, and more that are hosted directly on LinkedIn's platform. (You watch -- it's coming!)

The playing field has never been more level. Whether you're a solo entrepreneur, a small business owner, or a sales executive inside a Fortune 100 company, you all have the same shot at success when it comes to LinkedIn and similar platforms.

At the end of the day, the most creative, helpful, and enjoyable content will win.

It already does with LinkedIn's publishing platform, and the same will be true once LinkedIn begins inviting you and me to submit our best e-learning courses directly to the LinkedIn community at large (which I'm sure is one of the key long-term plays in acquiring Lynda).

Take a page from my parents: Teach!

So if you haven't already, you need to follow in the footsteps of my parents and start teaching. The good news for you is this: Your paycheck should be much higher than what my parents earned as English professors during 1970s.

(And yes, that's me in the photo above, circa 1978 or so. Note my mischievous grin ... perhaps I was already dreaming of how I'd make a living teaching others with some ideas of my own!)