Steven Stein likes to follow garbage trucks． His strange habit makes sense when you consider that he's an environmental scientist who studies how to reduce litter，including things that fall off garbage trucks as they drive down the road． What is even more interesting is that one of Stein's jobs is defending an industry behind the plastic shopping bag．

    Americans use more than 100 billion thin film plastic bags every year． So many end up in tree branches or along highways that a growing number of cities do not allow them at checkouts （收银台）． The bags are prohibited in some 90 cities in California， including Los Angeles． Eyeing these headwinds， plastic﹣bag makers are hiring scientists like Stein to make the case that their products are not as bad for the planet as most people assume．

    Among the bag makers' arguments： 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 has appeared as its replacement： reusable shopping bags． The stronger a reusable bag is， the longer its life and the more plastic﹣bag use it cancels out． However， longer﹣lasting reusable bags often require more energy to make． One study found that a cotton bag must be used at least 131 times to be better for the planet than plastic．

    Environmentalists don't dispute（质疑） these points． They hope paper bags will be banned someday too and want shoppers to use the same reusable bags lor years．

Teens and younger children are reading a lot less for fun, according to a Common Sense Media report published Monday.

While the decline over the past decade is steep for teen readers, some data in the report shows that reading remains a big part of many children’s lives, and indicates how parents might help encourage more reading.

According to the report’s key findings, “the proportion (比例) who say they ‘hardly ever’ read for fun has gone from 8 percent of 13-year-olds and 9 percent of 17-year-olds in 1984 to 22 percent and 27 percent respectively today.”

The report data shows that pleasure reading levels for younger children, ages 2-8, remain largely the same. But the amount of time spent in reading each session has declined, from closer to an hour or more to closer to a half hour per session.

When it comes to technology and reading, the report does little to counsel (建议) parents looking for data about the effect of e-readers and tablets on reading. It does point out that many parents still limit electronic reading, mainly due to concerns about increased screen time.

The most hopeful data shared in the report shows clear evidence of parents serving as examples and important guides for their kids when it comes to reading. Data shows that kids and teens who do read frequently, compared to infrequent readers, have more books in the home, more books purchased for them, parents who read more often, and parents who set aside time for them to read.

As the end of school approaches, and school vacation reading lists loom (逼近) ahead, parents might take this chance to step in and make their own summer reading list and plan a family trip to the library or bookstore.

 A build-it-yourself solar still (蒸馏器) is one of the best ways to obtain drinking water in areas where the liquid is not readily available. Developed by two doctors in the U.S. Department of Agriculture, it's an excellent water collector. Unfortunately, you must carry the necessary equipment with you, since it's all but impossible to find natural substitutes. The only components required, though, are a 5'×5' sheet of clear or slightly milky plastic, six feet of plastic tube, and a container—perhaps just a drinking cup—to catch the water. These pieces can be folded into a neat little pack and fastened on your belt.

   To construct a working still, use a sharp stick or rock to dig a hole four feet across and three feet deep. Try to make the hole in a damp area to increase the water catcher's productivity. Place your cup in the deepest part of the hole. Then lay the tube in place so that one end rests all the way in the cup and the rest of the line runs up—and out—the side of the hole.

   Next, cover the hole with the plastic sheet, securing the edges of the plastic with dirt and weighting the sheet's center down with a rock. The plastic should now form a cone(圆锥体) with 45-degree-angled sides. The low point of the sheet must be centered directly over, and no more than three inches above, the cup.

   The solar still works by creating a greenhouse under the plastic. Ground water evaporates (蒸发) and collects on the sheet until small drops of water form, run down the material and fall off into the cup. When the container is full, you can suck the refreshment out through the tube, and won't have to break down the still every time you need a drink.

This educational method was first observed in 2012 by Sonia Kieindorfer,a biologist at Flinders University in South Australia,and her collcagues.Femake Australian superb fairy wrens were found to repeat one sound over and over again while hatching their eggs,When the eggs were hatched,the baby birds made the similar chirp to their mothers—asound that served as their regular “feed me!”call.

To find out if the special quality was more widespread in birds,the researchers sought the red-backed fairy wren,another species of Australian songbird.Firstthey collected sound datd from 67 nests in four sites in Queenslang before and after hatching,Then they identified begging calls by analyzing the order and numberof notes.A computer analysis blindly compared calls produced by mothers and chicks,ranking them by similarity.

It turns out that baby red-backed fairy wrens also emerge chirping like their moms. And the more frequently mothers had called to their eggs,the more similar were the babies’ begging calls. In addition,the team set up a separate experiment that suggested that the baby birds that most closely imitated their mom’s voice were rewarded with the most food.

This observation hints that effective embryonic learning could signal neurological(神经系统的)strengths of children toparents.An evolutionary inference can then be drawn.”As a parent,do you investin quality children,or do you invest in children that are in need?”Kleindorfer asks.”Our results suggest that they might be going for quality.”

    A buld-it-yourself solar still(蒸流器) is one of the best ways to obtain drinking water in areas where the liquid is not readily available. Developed by two doctors in the U. S. Department of Agriculture, it's an excellent water collector. Unfortunately, you must carry the necessary equipment with you, since it's all but impossible to find natural substitutes. The only components required, though, are a 5' x 5' sheet of clear or slightly milky plastic, six feet of plastic tube, and a container-perhaps just a drinking cup-to catch the water. These pieces can be folded into a neat little pack and fastened on your belt.

    To construct a working still, use a sharp stick or rock to dig a hole four feet across and three feet deep. Try to make the hole in a damp area to increase the water catcher's productivity. Place your cup in the deepest part of the hole. Then lay the tube in place so that one end rests all the way in the cup and the rest of the line runs up-and out the side of the hole.

    Next, cover the hole with the plastic sheet, securing the edges of the plastic with dirt and weighting the sheet's center down with a rock. The plastic should now form a cone(圆锥体) with 45-degree-angled sides. The low point of the sheet must be centered directly over, and no more than three inches above, the cup.

    The solar still works by creating a greenhouse under the plastic. Ground water evaporates (蒸发) and collects on the sheet until small drops of water form, run down the material, and fall off into the cup. When the container is full, you can suck the refreshment out through the tube, and won't have to break down the still every time you need a drink.