Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: Electrons are always added to the lowest energy level first until it has the maximum number of electrons possible, and then electrons are added to the next higher energy level until that level is full, and so on. The maximum number of electrons at a given energy level depends on its number of orbitals. There are at most two electrons per orbital. Answer: the lowest
[A]: Electrons are always added to which energy level first?

[Q]: Passage: Models may be physical, conceptual, or mathematical. Answer: mathematical
[A]: Models may be physical, conceptual, or what else?

[Q]: Passage: Materials that have high resistance to electric current are called electric insulators . Examples include most nonmetallic solids, such as wood, rubber, and plastic. Their atoms hold onto their electrons tightly, so electric current cannot flow freely through them. Dry air is also an electric insulator. You can learn more about electric insulatorsas well as how to test whether a material is an insulatorby doing the activity at this URL:. Answer: electric insulators
[A]:
What do you call materials that have high resistance to electric current?