Coinbase is offering educational modules right on their platform and users get rewarded for watching these 2-3 minute videos and answering one simple questions based on the video.
In about 10 minutes, I received $10 worth EOS. That's not bad.
To earn the remaining $40 worth of EOS, you have to invite friends. There are only 4 invites possible worth $10 each. The total pool of EOS available for this educational module is limited. As such, it goes without saying that you should take advantage of this before it closes.
You will get your own referral once you complete your educational modules using which you can invite 4 friends.
Here is the Invite for the Coinbase EARN.
If you do not have a Coinbase account then use this link to open: Coinbase Account Opening referral.