Help needed for a year long curriculum mapping (K-5)

My school is thinking of introducing to the elementary students, and I see a course designed for K-5. The problem is: our school has a computer class once (40min long) every week throughout the year, and I am concerned about distributing the course materials over a year-long period for each grade.

Given that each grade level course takes about 10-25 hours, I assume students can use each grade level program for 3 months to a max of 8 months, which is a little short for the entire year. It would be great if you could give us some suggestions on this.

Thanks a lot!