The Snail House Sure is Carefree

Nobita gets called a liar by his mom when she believes him to be hiding his recent exam. Nobita complains to Doraemon and exchanges his snacks for a snail shell that protects him from his surroundings. Shizuka shows up near the end and returns a journal that holds his exam grade. Nobita's mom apologizes, but is met with Nobita's demands... until she asks him for his grade