Watering the lawn should include

using water efficiently (i.e., adhering to the prescribed application rate)
determining the best time to water
testing the turgor of the grass
acquiring and using rainfall data
watering the entire lawn with one inch of water per week and soaking the soil to a depth of 4 to 6 inches, allowing the water to reach deep into the root system.

Process/Skill Questions:

How can overwatering hurt a lawn?
What are the signs that a lawn needs to be watered?
What is turgor pressure?
How does one calculate the 1- to 1.5-inch watering rate, and why should rainfall amounts be considered?
What are the factors one should know in order to determine watering needs?