Nobita late for school

If you dunno who is Nobi Nobita, he is a 10 years old boy from the comic book (or cartoon) named "Doraemon". He is a lazy boy who always get a 0 in his test. He always get Suneo and Chaien bullied him. He also late for school. But, Doraemon, a gadget cat from the future see Nobita's trouble and he decide to go back to the pást and help him.