This worksheet serves to provide a basis for understanding the disbelief in plan proposed by Christoper Columbus to the Spanish monarchs. You can introduce this worksheet by explaining that this map represents what Europeans (more or less) knew of the world in 1492.
The students are directed to simply draw a line from Spain to China or India (You may have to point out these places to students) without touching land, representing the voyages to get to the East Indies for trading.
Students may think this seemingly-too-simple task is a trick. The vast majority will draw a line that goes south around South Africa and up through the Indian Ocean. This represents the voyage that many explorers (Portuguese and Spanish) were taking prior to 1492. Ask students "Why did you go around Africa?" and they will say "because it's quick or easy" or even "because I didn't want to cross the entire ocean'.
You can use this as a jumping board into the conversation about how very few people believed Columbus when he suggested going across the vast ocean.