I can't help with Let's Go Learn, but if she is open to a book-based programme, the "Keys To" series does stick to a single topic at a time (Key to Fractions, Key to Decimals, Key to Percents, etc.). The workbooks are very inexpensive, and answer keys are available.

Here's the address: http://www.keypress.com/x6469.xml

Hope that helps!

peace
minnie