and i'm just grabbing for all the gusto i can get. >> brown: arthur lithgow died in 2004. son john performs "stories by heart" on broadway through early march. for the pbs newshour, i'm jeffrey brown from new york. >> woodruff: smart phones have surely changed the way we live-- including the way kids interact with and use that technology every day. there are growing concerns about what that is doing to children and that is the focus john yang has for us tonight as part of our weekly segment, "making the grade." >> yang: judy, earlier this month, two big shareholders in apple jumped into this debate. together, jana partners, an investment management firm, and the california state teachers retirement system own about $2 billion of apple stock. they called on the iphone maker to come up with ways for parents to restrict the amount of time children spend on iphones, and to study the effect heavy usage has on kids' mental health. to discuss this, we're joined by charles penner, a partner at jana partners, and by jean twenge, a san diego state university psychology professor and