Choose refillable fountain or ballpoint pens, wooden pencils and rulers, paper or card folders, and metal sharpeners. Reuse last year's kit before buying new, and ask schools to stop laminating.
A year of disposable pens, plastic pockets, glue sticks and laminating is around 300 g of plastic per student. Eliminating and reusing sits at the top of the Ellen MacArthur Foundation's upstream-innovation hierarchy.
The catch: some schools mandate specific plastic items; a class or parent-teacher request to change the list has more effect than one pencil case.