Final answer:
The item that would NOT go in la mochila is 'la puerta' which means 'door'.
Step-by-step explanation:
La mochila is the Spanish word for 'backpack'. Among the items listed, 'la puerta' would NOT go in la mochila because it means 'door'. The other items, 'la hoja de papel', 'el bolígrafo', and 'el lápiz', all refer to school supplies that would typically be found in a backpack.
Learn more about Inclusion in la mochila