There is no required homework. But, some students are eager to get a head start or engage in projects that promote learning and are fun. Below are suggestions to help you learn and challenge yourself. Note that the projects suggested are not easy. They are meant for those who already have coding experience.
Enjoy the learning. Be creative. Have patience. Use your grit!
Python - Intermediate Data Programming
If you want to learn some Python with Data Science and Machine Learning, check out Kaggle. There are many different courses listed there that overlap considerably with UW's CSE 163 - Intermediate Data Programming. The Kaggle site will lead you through learning Python, Machine Learning, Pandas, Data Visualization and more.
Advanced Programming Topics
If you wanted to learn some Data Structures, check out the projects on UW's CSE 143 - Computer Programming II page. The site posts projects from past quarters that you can attempt to do. It's a tough course and a tough set of projects, especially without direct instruction. But, without the deadline pressure, it can be fun. Well, for me it was.
There are some videos you can watch to help get you going, too.
AP Computer Science A
You can check out this video page with videos that cover all the material covered in class.
To practice, check out Code-Step-By-Step which has a lot of practice problems in a multitude of programming languages.
Projects and Puzzles
If you want to solve some mathematical puzzles, check out ProjectEuler.net. There are lots of math problems where the answer is a simple number. Some of the math concepts are deceptively simply, but finding the numerical solution is hard! Start on the "easy" problems. To solve most of the problems, you'll need to be familiar with Data Structures and Time Complexity Analysis because the most straight forward solution could take hundreds of years of computing time.
Go to the Stanford Nifty website and find a project that perhaps is in your wheelhouse. These are projects posted by professors all over the country who find them to be good instructional assignments.
Perhaps you simply need an outlet for your creative juices. Code your own project! I recommend getting familiar with GitHub to save your code and get exposed to some good Project Management tools.
Many students enjoy creating games with graphics. For example, try creating a simple graphical, two-player game of Tic Tac Toe using the University of Washington's DrawingPanel. If you're looking for more intensive graphics, do a search on "game engines" where you'll discover some popular engines to help you build professional looking games using: Unity, Game Maker, GoDot and many more!