The trick with lie and lay is to realize that "lay" plays two roles. "Lay" in the present tense means something like "to put" or "to place." In the present tense, "Lay" usually takes a direct object (though it doesn't have to.) For example, "Players lay the ball down as soon as the whistle blows."

Confusion comes in because "lay" is also the past tense of the verb "lie," which means "to recline." Lie never takes a direct object. So, if you put something down in the present, you use the word "lay." And if you reclined in the past, you use the word "lay." If you put something down in the past, you use the word laid. For example, "The player laid the ball down after the coach blew the whistle."

If you recline in the present, use the word "lie." For example, "I need to lie down because I have a headache from trying to understand 'lie' and 'lay.'"

OK. Why don't you try a few exercises now.