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>> welcome to "teen kids news." i'm veronique. here's this week's top story. ? sports are supposed to be good for us. they get our heart pumping, build muscle tone, and increase but if we're not careful, some sports can cause hidden injuries. alexa has the story. >> julia runs track. like many athletes, she puts in long hours training and competing. and like an increasing number of athletes, she now suffers from pains that don't seem to come from a particular injury. >> we never really figured out why. we think it was just from overuse mostly, just from trying to put more miles in than i

>> roughly, with just practice time it would be about 17 hours, but with games, that will add on at least 2 hours a day. >> i practice like 15 to 20 hours a week. >> i spend 12 hours a week practicing for track. >> probably around 20 hours a week, between the weight room, playing lacrosse, practice, stuff like that. >> in fact, according to dr. thomas best, many teens put in up to 18 hours a week doing sports. between the amount of time that they're spending and the increased incidence of injuries. >> the type of injuries dr. best is talking about tend to be caused by repeating the same motion over and over. this repetitive motion puts extra wear and tear on certain parts of your body. working with ohio state's wexner medical center, dr. best studied thousands of sports injuries. he believes that injuries from overuse are on the rise. that's because some sports have

no longer just seasonal. therefore, there's more pressure to practice a specific sport all year round. >> i play varsity lacrosse exclusively. yeah, i dedicate most of my time on that. >> i run track like all year 'round. >> i play lacrosse at colgate university. >> i do cross-country, and i do winter and spring track. >> it's speculative at this point, but many of us feel that sport specialization is leading to -- it may, in fact, be the leading risk factor for overuse injuries. overuse are the lower leg, the knee, and the shoulder. those are where you're likely to get... >> i've had a hip flexor recently before a big meet that i had. i wasn't supposed to run, but i did and made it worse, but i kept running. >> i have gotten an overuse injury, yes. it did. it sat me out for a couple weeks. >> i have gotten a sore tendon.

>> the key to avoiding these is changing your game -- literally. >> when you play a different sport, you're using different muscle groups. so, that gives your -- you know, the other groups, if you will, a relative break. >> girls are more likely to suffer from overuse than boys. so it's not surprising that three of the top four sports most likely to cause repetitive-motion injuries are sports that girls play... for guys, it's swimming. besides avoiding spending too much time on any one sport, here are some other ways to avoid repetitive-motion injuries. make sure you're warming up properly both before and after playing. get plenty of rest and good nutrition. we girls especially don't get all the calcium needed to ensure our bones are strong. so, if eating dairy products is

about taking a calcium supplement. for "teen kids news," i'm alexa. >> can you really ride a bike with square wheels? to find out the answer, you need to know math, and that's why we're here at this rather unusual museum.

>> the famous astronomer galileo said that we can't understand the world around us without first understanding math.

surprisingly fun. scott tells us more. ? >> the national museum of mathematics welcomes visitors of all ages seven days a week. >> they make, like, games, you know, and you're learning and you don't even notice. >> so, people think that math is just about, you know, numbers and symbols all on a page and incomprehensible equations. and we want to show people the meaning behind the math. east side, the museum is chock-full with all kinds of hands-on displays and activities. so, what are the five most interesting exhibits for teens here at the museum? >> well, come on, scott. how about i show you? >> all right. ? our first stop is the human tree. that's what you turn into when you step in the red circle. you can change the seasons and even create intricate combinations. the point of this exhibit is to

one unit and you repeat it over and over again, ever smaller each time. and so you'll notice that each generation of this tree is another copy of you and of me. we're just getting smaller and smaller. >> when it comes to learning about patterns, you might say this exhibit on fractals is "tree-mendous." let's move on to number four. >> so, let's come to the fourth exhibit now, number four. this is called harmony of the spheres, and this is an exhibit that focuses on the relationshipet and music. and the way it works is that each one of these balls represents a chord, a chord that has three notes, which is also called a triad. so, when i touch that, we're hearing a chord. >> depending on which spheres you touch, you can actually create not just different music, but different emotions. >> i can show you that, on this side, we have a minor chord. [ minor chord plays ] that sounds kind of sad, whereas on this side, we have a major chord. [ major chord plays ]

>> it's musical math, and this is one of two music and math exhibits we have in the museum. there are a lot of relationships between math and music. [ chords playing ] next is number three. ? the math square is a colorful way to show relationships. for example, here, it's drawing a border around each kid to literally prove a point. >> that border shows all the points on this square that are closer to them than to any other person on the square. so, you might have a very big portion if there's nobody near you, or if there's lots of people standing around, you'll all get very small portions. >> okay. well, do you mind if i try it out? >> not at all. let's step right on. ? you've got a very big region. i've got a smaller region because i'm sharing with this young man.

the first step is designing an image on the computer. >> the best part about this is, not only is she creating something beautiful, but we can then print those on our 3-d printer. >> not every design gets printed. visitors vote for their favorites. the images receiving the most votes are transformed from computer images, into physical objects. >> so, this actually prints out what kids have drawn in a three-dimensional shape. >> yes. layer after a layer after a layer. >> the objects created by the three-dimensional printer become part of the exhibit. when we return, we'll find out what the most popular exhibit

? >> we're touring the five most popular exhibits at the museum of mathematics. so far, we have learned about

designing in three dimensions -- proof positive that math is anything but dull. >> at first, i was kind of skeptical. i was like, "a museum about math?" but then we came in, and it was so much fun. >> a lot of people, when they hear about a museum for math, may think it's boring. so, what did you think? >> i thought it was pretty cool. >> so, would you tell other kids to come here, and what would you tell them was fun about it? >> um...everything. >> and the top exhibit here at the museum of mathematics? >> now, this is the most popular exhibit in the whole museum. this is our square-wheeled tricycle exhibit, and what's so surprising about it is that you can ride on bicycles that have square wheels and your ride is perfectly smooth. >> the secret is the design. the wheels and the bumpy surface they ride on fit together with mathematical precision. for all you math mavens, it has to do with what's called a catenary curve. >> and so the square wheels -- the point of the wheel is

of each hump. and so you get a perfectly smooth ride because the bicycle seat is not going up and down, but the wheel mates perfectly with the track. and that's one example of how mathematics can make the seemingly impossible suddenly possible. >> math at its finest. >> absolutely. while they say seeing is believing, i needed a test ride to be convinced. amazingly, it was just like riding a bike with round wheels. no question about it -- all the exhibits here add up to a at the national museum of math, i'm scott for "teen kids news." >> in the morning, if you have a hard time paying attention at school, it may not be your fault. there's now scientific evidence that teens don't learn well when they have to get up early. that's why the american academy of pediatrics is recommending that schools shouldn't start before 8:30 a.m. high schools in california, oklahoma, georgia, and new york

shift to a later start time. >> this important message is brought to you by the national road safety foundation. >> this is katie, and i'm -- well, you know who i am. life's going great for katie -- class president, captain of her soccer team, and just aced her sats. and she loves to text. ? but i know something she doesn't. see that intersection? a car will be going through it in precisely three seconds. i'll give her today, but tomorrow, who knows? >> beneath this stately dome, many of england's most historic ceremonies have taken place. coming up, we'll visit

>> one of the greatest disasters

world one of its greatest places of worship. nicole explains in this "u.k. o.k." report. [ "rule, britannia!" playing ] [ fire crackling ] >> back in 1666, fire swept through london. because so many of the buildings crowded together were made of wood, the fire raged out of control for four days, destroying two-thirds of the city. seven out of eight londoners were left homeless. almost 90 churches were destroyed, including the giant st. paul's cathedral. king charles ii commissioned christopher wren to help oversee the rebuilding of the city. ? wren's masterpiece would be a new st. paul's.

to complete. its iconic dome is one of the largest in the world and was modeled after the dome of st. peter's at the vatican. for more than 200 years, st. paul's reigned as the city's tallest building. during world war ii, london was often bombed by the germans. amazingly, st. paul's survived. ? over the centuries, the cathedral played a central role important state events, including the funerals of the great naval hero admiral nelson and prime minister winston churchill. ? but not all occasions were so solemn. this is where lady diana spencer got married and became princess diana.

queen ? >> i, charles philip arthur george... >> "take thee, diana frances..." >> ...take thee, diana frances... >> "...to my wedded wife." >> ...to my wedded wife. [ "god save the queen" playing ] >> this impressive building still echoes with the pomp and glory that were once the british empire. you can climb to the top of the dome and gaze out on modern london. the view is spectacular. reporting for "teen kids news," i'm nicole. >> ? god save the queen ? [ bat cracks ] [ cheers and applause ] >> one of the best parts of the major league baseball regular season is the all-star game. since 1933, the midsummer classic, as it has been nicknamed, has featured the best players from the american league play the best players from the

now, the reason that this all-star game is so important is because the winning league gets home-field advantage in the world series. i'm matt with "teen kids news." >> here's a poem on a fact that's little-known. there's one part of our body that never grows. i'm not talking about our bones, our ears, or even our nose. the answer is pretty easy to see. it's our eyes. from the time we're born until we die, they never change size.

>> if you've always wanted to learn how to bake, this next story is for you. katie shows that you don't need to be a whiz. >> meet elizabeth jean. when it comes to making pies, she's an expert. so, what kind of pie are you gonna show us how to make today? >> katie, today we're gonna make one of my favorites. it's caramel apple pecan. and we are going to use a rolled

refrigerator section at the grocery store. so, why don't you go ahead and unroll this? we have our tin ready. and we're just gonna place this right in the center. >> ah, this is so easy. >> it's so easy. yup. there you go, and just -- perfect. >> cool. >> what we've already done is we've already diced our apples. we've used a peeler, and we've also used a knife. so, please make sure at home, you know, when you do this, to be real careful. we also have already mixed our spices, okay? some flour, or some kind of starch just so we get a nice sauce -- some cinnamon. so, why don't you go ahead and put that right over our apples? looks great. you're doing a great job. and then we're just gonna give it a quick little mix. why don't you go ahead and do that? >> it smells really good. >> isn't that delicious? i'm gonna move this out of your way so you can put that right in front of you.

okay, so, i'm going to use the spoon, okay, that we just used to mix everything with and just put the apples right on top. all right. >> mmm. >> so, last but not least -- this is really easy -- what we're gonna do is unroll the top crust. and we're gonna just place it right on top. >> cool. >> whoops. there we go. perfect. so, we're just gonna line it up. all right, so, now here's the trick to all of this. got the top and your bottom crust, and you just want to bring them together and pinch them, okay? >> okay. >> and as you're doing that, take it -- katie, can you see this? -- and then just fold it under. >> fold it under and pinch it. >> yup. fold it un-- i'll do this side, and if you do that side, we'll meet. all the way around. oh, you're faster than i am. i think you've done this before. [ both laugh ] >> i love to bake. >> it is fun.

eaten a lot of pies at a lot of family functions, whether it's thanksgiving, the fourth of july, or a birthday party. so they certainly have been a big part of our family tradition and gatherings, you know? >> they make the kitchen smell great. >> they sure do. so, now what we have -- so, now our crust is ready to pinch. >> mmm. >> some people get nervous when it comes to this part. so, you can either take a fork, the back of a fork, and just push it down all the way around, or what i ke hand, pull it up, and pinch. >> ahh. >> see how cute that is? >> so, pull it up... >> yep. >> ...and pinch. >> all the way around. >> ah, okay. >> just keep going. oh, that looks beautiful. you have done this. i'm -- this is great. you can be my assistant anytime. [ chuckles ] >> okay, we're almost done here. >> you almost got it? >> yeah. >> perfect. >> there we go. >> last but not least, before we stick it in the oven, we're going to just put a couple of

bubble over the -- okay, so, we are ready to go. >> wow! >> so, all right, let's just stick this in the oven. >> okay. >> we're gonna bake it at 375 for about an hour. >> okay. >> you can tell when it's done just when it's -- you'll see when it starts to bubble a little bit. >> mmm. >> okay? >> what color is it gonna be? >> it'll be a kind of a golden brown... >> okay. >> ...i would say. that's when you kind of know when it's complete. but, anyway, you'll really start to smell it. when you smell that apple pi really close to it being done. okay, katie, it is ready. let's take this out. it smells delicious. >> yeah. i'm excited. ooh, it looks delicious, too. >> wow. so good. mm-hmm. all right, i'm just gonna set this down. i'm gonna have to grab this so it doesn't skid on the counter, okay? >> yeah. >> just gently push this off.

take this out of the oven 'cause it's really hot. and then we're just going to finish this up with some caramel. so, go ahead and pour some caramel. just drizzle it right over the top of there. >> okay. >> and just kind of get it all over. wonderful. keep going. looks good. >> should i do all of it? >> yep, yep, we're gonna do all of it. >> mmm. >> that's the beauty. >> that makes it smell even better. >> oh, my goodness. isn't that amazing? >> wow. >> perfect. and then we're gonna put about half of those... >> that there. half of these? >> ...pecans on there. yep, and we'll just see how it looks. >> should i just sprinkle it? >> yeah, sure. sprinkle them. that's perfect. >> mmm. now, are these the only nuts you can use? >> you know what? you can use any kind of nut that you would love. i mean, there's really -- there's no guidelines to...

would like. it's just your preference. >> okay. >> okay. that looks fabulous. >> cool. >> look at this. >> so, a kid can make a pie just like this from a kit? >> from a kit. yes. i am the creator of the pie kit. so, now everyone can make a homemade pie at home in just minutes. >> wow. >> and it's foolproof. look at this. anyone would be happy to serve this at their next family function. >> yeah. the only thing better than making a pie is eating it. delicious. for "teen kids news," i'm katie. now let me just take another bite to make sure it's the real deal. ? >> that looks really good. we'll see you again next week with another edition of "teen kids news."