Answer:
Earth's day and night.
Step-by-step explanation:
If Luis has stuck a toothpick vertically through the center of the Earth model and then used a flashlight to shine light on part of the earth while spinning the model Earth, he is most likely trying to model Earth's day and night.
Earth's day and night occurs because of its rotational phenomenon. As it rotates around its axis, the part facing the Sun is the daytime while the part of Earth that does not face the Sun is the nighttime.