Consider a game in which you flip a coin. if it comes up heads, you earn 1 point; if it comes up tails, you earn 0 points. what is the expected value of one coin flip?

Well, A coin has 2 sides (Heads and Tails), so theres a 50% of you getting a point at all. Same thing goes to spinning a spinner. If theres only 2 sections, theres a 50% chance that you'll hit one section over the other (Unless one of the sections is bigger than the other, which is not the case here, since a coin has an equal radius throughout the entire circle).