Here is a little example of how our child has decided to mix two languages. Normally she seperates them very well, but it was late and she just put whatever out there. Too funny! In red are the words in english that she put in french. But what is impressive, is that instead of using a word in french for buy she took the word in english and tried to make it french by adding the -er, which works sometimes (just not in this case).
Maman, elle va au store. Elle va buyer les goodies.
(Mommy's going to the store. She is going to buy goodies)