Tommy,
Wanting to fill your free time with Catholic things is great, but until you spend an appropriate amount of time on your studies and any chores or other obligations that you have your time is not really “free time.” This is the time when you are laying the foundation for the rest of your life. It may not seem like a huge deal to go from As to some Bs at this point, but you don’t know what your future holds. It could mean the difference between getting into the college of your choice or getting a certain job that you really want later in life.
You honor God by making the best possible use of the gifts that He has given you. Clearly you were capable of making better grades in the past, so He did gift you with intelligence. Remember the story of the servants who were given different amounts of money by their master to invest? One of the take aways of that Bible story was that to whom much is given, much is expected. You don’t have to be actively praying or watching EWTN or reading your Bible to be honoring your faith and your God. When you do your very best at homework or at school, you can offer those things to God in thanks for all that He has given you!
You can pray little things all day while still taking care of your obligations. You can silently pray on the way to school and offer your day and all of your work to God and ask to do His will that day. You can make a short prayer in between classes thanking God for the opportunity to go to school in a world where so many people don’t have that opportunity or thanking Him for your friends or teachers. You can pray something like The Angelus at 6am, noon and 6pm without skipping chores, homework or school.
If there are some shows you really want to see on EWTN when you should be working on schoolwork or chores, can’t you record them and save them for free time on weekends or after your work is done?
I really pray that you find a way to honor God without wasting one bit of the talent that He has given you. Maintaining the best grades possible becomes even more important as our economy slumps and tuition and other costs increase for college. Earning a scholarship for college or other vocational training can be a gift that you offer back to God and also use to honor your family for providing you with a home and the ability to go to school.
May God continue to bless you!