3 . The other day, my sister and I were sitting in a restaurant, trying to have a conversation, but her children, four-year-old Willow and seven-year-old Luca, would not stop fighting. The arguments—over a fork, or who had more water in a glass—never stopped.

Then my sister reached into her handbag, produced two shiny iPads, and handed one to each child. Suddenly, the two were quiet. They sat playing games and watching videos, and we continued with our conversation.

After our meal, as my sister stuffed the iPads back into her bag, she said, “I don’t want to give them the iPads at the dinner table, but if they keep them occupied for an hour so we can eat in peace, I often just hand them over. I’m afraid it’s bad for them. I do worry that it makes them think it’s OK to use electronics at the dinner table in the future.”

Dr. Gary Small, director of the Longevity Center at the University of California, Los Angeles says that the brain is highly sensitive to stimuli (刺激物), like iPads and smartphone screens, and if people spend too much time on one technology, and less time interacting (互动) with people like parents at the dinner table, that could prevent the development of certain communication skills.

“Conversations with each other are the way children learn to have conversations with themselves, and learn how to be alone,” said Sherry Turkle, a professor of science, technology and society at the Massachusetts Institute of Technology. She fears that children who do not learn real interactions, which often have imperfections, will come to know a world where perfect, shiny screens give them a false sense of intimacy (亲密) without risk. However, they need to be able to gather themselves and know who they are. So someday they can form a relationship with another person without a panic of being alone. “If you don’t teach your children to be alone, they’ll only know how to be lonely,” she said.

10 . Steven Stein likes to track garbage trucks. He says, “It’s hard to resist.” Stein’s strange habit makes sense when you consider that he’s an environmental scientist who studies how to reduce litter, including stuff that falls off garbage trucks as they run down the road. What is even more interesting is that one of Stein’s current plans is defending an industry behind a source of trash: plastic shopping bags.

Americans use more than 100 million plastic bags every year. So many end up in tree branches or along highways that a growing number of cities are banishing (排除) them from checkout lines. The bags are outlawed in some places in the USA.

Facing these situations, plastic-bag manufacturers are hiring scientists like Stein to make the case that their products are not as bad for the planet as most people assume. “It’s important to base your decisions on facts,” says Stan Bikulege, CEO of Hilex Poly, which has hired Stein.

Among the bag makers’ argument: many cities with bans still allow shoppers to purchase paper bags, which are easily recycled but require more energy to produce and transport. And while plastic bags may be ugly to look at, they represent a small percentage of all garbage on the ground today.

The industry has also taken aim at the product that can take the place of plastic bags: reusable shopping bags. The sturdier a reusable bag is, the longer its life and the more plastic-bag use it cancels out. But this plan has another side. Longer-lasting reusable bags often require more energy to make.

Environmentalists don’t agree with these points. They hope paper bags will be banned someday too and want shoppers to use the same reusable bags for years. So are reusables our destiny? The answer is probably yes. And Andy Keller, inventor of reusable polyester (聚酯纤维) bags, says, ”If you can carry it out in your hands or put it back in your car, you don’t need a bag.”