Attach a string to a box and use as a pull toy. Open ends of a large box for a tunnel. Small boxes of graduated sizes make a nesting toy. A large box turned bottom-side up becomes a table. A tall box can be an easel.
Boxes covered in colored contact plastic are blocks.
Cut one end from a shoe box and turn upside down for a garage for toy cars. You can probably think of several more. As a teacher of children, you have a tremendously important ministry to provide week after week. You continue your ministry with the children because you know God called you to the work. However, the joy of serving Him is sometimes clouded by some struggle.