If you're going all-out on an Angry Birds School Supplies theme, you can get hold of a whole host of the bird bags - small plush backpacks, larger backpacks, messenger bags and even large tote bags which are better for shopping than school.
Younger children tend to like the little backpacks because it's easy for them to carry on their way to school. My young daughter, who's coming up to age 5, even manages to carry her backpack without complaint on our long walk to school every morning.
The small, plush Angry Bird Backpacks are so cute for little kids who can't carry large bags very well themselves. My little girl uses her backpack to carry her plastic lunch box. Her school issue her with a large book bag which holds a large, regular sized cardboard folder for homework and her reading books.
Slightly older kids will probably think that Messenger bags are better and cooler-looking. These have an adjustable shoulder strap so the bag can be slung across the body. I see lots of older kids age 8 plus who wear messenger style bags on their bikes.
Whatever Angry Birds bag you get, do check out the product dimensions to see if it will carry what you want it to.
The great thing about shopping with Amazon is how good they are at accepting returns (you may have to pay a nominal postage fee if the item being returned is not faulty) if you receive something and it isn't quite right. That way you can see for yourself if the bag is suitable before making your mind up. I've bought loads of shoes for my daughter this way.