When learning about the Addition Rule in probability, students sometimes make a few common mistakes. Here are some things to look out for:

1. Ignoring Overlap: One big mistake is not thinking about whether two events can happen at the same time. For instance, if you roll a die, the events "rolling a 2" and "rolling an even number" overlap. That's because 2 is an even number!

2. Wrong Formula: The right formula to use is $P(A \cup B) = P(A) + P(B) - P(A \cap B)$. This formula helps us remember to account for any overlap. If you forget to subtract $P(A \cap B)$, your answers might be wrong.

3. Mixing Up Percentages and Probabilities: Sometimes, students get confused between percentages and probabilities. Just remember: a probability is always a number between 0 and 1.

By keeping these tips in mind, students can get better at understanding the Addition Rule in probability!