How do you raise the 50 settlers required for the last tablet in the economic-demo-scenario?

I'm having trouble understanding how that feat works?

What makes settlers wanting to join your colony and line up on the sideline until you accommodate them in a house?

I had trouble with this too, it just takes a bit of time, just expand lots and make sure you've got lots of School's as this brings in more settlers.

Schools ... hmm ... I'll try that, see what happens.

Yeah, that did the trick, 4 schools later and I had enough settlers to choke a whale.