One-sided test

You choose the direction before you look at the data, based on the claim being investigated, and the p-value is then the area in that single tail of the null distribution. In AP Statistics the null hypothesis is tested at the boundary of equality even when the alternative points one way. For example, with $H_a: p > 0.50$ and a test statistic of $z = 1.75$, the p-value is $P(Z > 1.75) = 0.0401$. A one-sided test detects a given effect more easily than a two-sided test, but only when the effect runs in the hypothesized direction, which is exactly why picking the direction after seeing the data is cheating.