One Fish, Two Fish, Red Fish, Blue Fish Activities:
The obvious thing is to read Dr. Seuss' One Fish, Two Fish, Red Fish, Blue Fish book. We read it once and then also a second time where N had to stand up and act out what was going on on each page. That was a lot of fun!
We printed out a free activity sheet on opposites based on the book from Seussville.com to go along with the story.
The night before I cut plain foam sheets into simple fish shapes in various colors. I dumped them in the bathtub and had N go "fishing" with a spoon to catch them all. He had to sort them into containers based on color and afterwards he counted them all by color and determined which colors had the most and least fish.
On our whiteboard I wrote rows of rhyming words from the story with one word that doesn't rhyme per row. I read him the words and had him circle the word that didn't rhyme.
He made a Wump out of play-doh. The Wump in the story has 7 humps, his only had 6 but he didn't mind!
And lastly he made his own art page based on the cover of the book: