Chapter Book Read Alouds for a 4 year old

The past few weeks we've been adding read aloud time to the end of Isaac's quiet time.  I am excited to be entering chapter books with him!  Our favorite series so far is the Magic Tree House Books! 

They are a great series for beginning readers (or beginning chapter book listeners) because they do have a picture every 5 pages or so and the stories are fast paced and easy to follow.  I have loved how Isaac now plays "Jack and Annie", pretending that he is a charater in their stories.

We checked out an audio version from the library and loved it too!  The author reads the stories and uses different voices for each charater. 
Here are a few other beginning chapter book series on our to read list:
-The Boxcar Children
-Ready, Freddy
-The Magic School Bus Chapter Books