Q - How is D3 different from user interaction manipulating DOM elements?
A - the DOM is manipulated by data
Q - how do I add D3 to my app?
A - minified file, CDN, unminified (we did <script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script> in class)
Q - Assuming a model and controller exist, where would I write a custom helper method that is available application wide?
A - (ApplicationHelper or application_helper.rb)
Q - What built in helper method renders a long number in human language?
A - <%= number_to_human(2342342352352) %>
Q - Where could I override a rails default behavior like changing the plural of cactus to cacti?
A - config>initializers>inflections.rb