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

Passage: Any magnet has two ends called poles where the magnetic effect is strongest. Answer: poles
What do you call the two ends of a magnet where the magnetic effect is strongest?

Passage: Cells are the tiny building blocks of living things. They couldn't be discovered until the microscope was invented. The discovery of cells led to the cell theory. This is one of the most important theories in life science. Answer: cells
What are all living things made of?

Passage: The Sun gives off energy in tiny packets called photons . Photons travel in waves. Figure below models a wave of light. Notice the wavelength in the figure. Waves with shorter wavelengths have more energy. Answer: photons
What are the tiny packets of energy the sun gives off called?