Go to Tapspace.com and browse the catalogue based on your available instrumentation (do you have a 5 octave marimba or only 4.3 (low A)? What type of accessories can you provide or at least sound similar? Find something fun and exciting in those areas. If there's a drumset part, but you have more kids than parts, double/triple/quadruple the amount of drumset players (they probably have one at home that they will WANT to bring to school). Keep it light and fun. Give it a year. Next year you'll be able to do more serious (musical) stuff because the kids will have a better understanding of the genre.