partitioning - How do I resize partitions using the simple installation wizard (installing a second Ubuntu)?

I'm running 11.10 and installing 12.04 LTS Beta 1 off a DVD. Using the installation wizard, I picked "Install 12.04 LTS alongside 11.10".

I am presented with a slider with approx 240GB on the left side and 60GB on the right. No other labels are present. I don't want to use the advanced partitioning tool. Which side is which Ubuntu?

If it's relevant: I am installing only for testing purposes (I've been caught by kernel regressions before), so I want to give 12.04 the minimal amount of space required. Once the final release is made, and I've tested that too, my plan is to remove the second partition and upgrade 11.10 to 12.04.