Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: The alkaline earth metals include beryllium, magnesium, calcium, strontium, and barium. Strontium and barium react with air and must be stored in oil. Answer: alkaline earth metals
A:
Beryllium, magnesium, calcium, strontium, and barium are classified as what type of metals?