My children store their reading trade books in large Ziploc bags. We call them their Bag Books. They always have three books: one they are presently working on, one they just finished and is now an old favorite, and a new one that they’ll be beginning soon. These bag books make sustained silent reading (SSR) easy. Each child has one to practice, one that’s an old friend, and one that’s a challenge to look forward to. They also bring these spill-proof bags home once a week to share with their parents.