Nana's Paint Mix Up Part 1

This applet is based on Dan Meyer's lesson "Nana's Paint Mix Up." Watch the video here: [url]https://vimeo.com/87211369[/url] and "fix" the mix up. Then play with the graph below. Toggle the slider to get a sense of how we can graph the color mixture.

How does the line change as you toggle the slider? Can you explain why this might happen? Hint: what do you think each axis represents?