on our broadcast tonight, deep debt. a crushing burden for millions of young americans and what the president revealed today about his own student loans. star witness in the case against john edwards, explosive revelations today in open court. mad cow, the first confirmed case of mad cow disease in the u.s. in six years. tonight what the experts are telling us about it. and teacher of the year, with over three million teachers in america, what makes her the very best. "nightly news" begins now. captions paid for by nbc-universal television good evening, there are warnings tonight that there's a financial timebomb set to go off

if congress doesn't act. the interest rate on a popular student loan is set to double. and this is not just a financial problem for the kids who are seeking a college education and their parents. student loan debt is now a national problem, it's larger than credit card debt and car loans, it's exploded in a bad economy right as millions are seeking that american dream of a college education. president obama talked about this on the road today. in fact he did something he's never done, talked in detail about how recently he paid off his own student loans. >> we only finished paying off our student loans about eight years ago, that wasn't that long ago. and that wasn't easy. especially because when we had malia and sasha, we're supposed to be saving up for their education, and we're still paying off our education. >> the president earlier today

in north carolina. nbc's john yang has more tonight on how hard it's become to pay for college. >> reporter: college graduation season is right around the corner, and for millions of students, the joy of achievement can be accompanied by dread. the average senior will leave college this spring with a diploma and student loans totalling more than $24,000. a new life with old debts. at new york university, some students owe even more. >> i'll be facing 80 grand worth of debt when i leave. >> looking at close to a quarter million dollars. >> 250,000. >> those burdens could soon grow. on july 1st, the interest rate on a popular government loan programs is set to double to.% unless congress acts. nearly 7.4 million students have staff order loans, averaging $11,000 each.

the higher rate would cost each of them more than $5,000 in higher interest payments. >> it's not going to stop them there going to school, i think what we may see, they may have more trouble on the back end paying these loans, the default rate could go up. >> the economy has dealt students a double whammy. often their patients can't afford to help them with with tuition, so the burden falls on them. with half of grads even unemployed or underemployed, paying back those loans can be hard. >> there's an impact on the broader economy because they don't have as much money to spend. that money should it be put back in the economy, could help us a good deal. >> reporter: planning how to pay for college should start early. >> you need to start figuring out what you can afford to spend when your child is just entering high school, and choose schools that have a wide range of affordability. >> reporter: to try to make sure the cost of a college education doesn't outweigh the future

dividend it promises. john yang, nbc news, washington. let's talk about this tonight with with chuck todd who's with us inned studio. isn't this a topic on which romney and obama agree? >> and also mitch mcconnell and other republicans, they all seem to agree this has to be changed right now, the economy is in such a place they have to do it. what's the motivation behind what the white house is doing? it's called election year politics. he was in north carolina today, he's now in colorado. tomorrow he will be in iowa. this isn'tage official trip, but it has the trappings of a campaign trip. he has a feeling about debt and the economy, so he's trying to get back in touch with them. >> tonight while it may not feel like it to ray lot of folks, is another primary night. >> biggest one since super tuesday.

you're going to hear mitt romney claim victory of the nomination, accepting the fact that after 43 frimry nights and caucuses he now accepts this idea that he's the presumptive nominee. he's going to use a few lines tonight, all focused on president obama. we've seen hopes and dreams diminished by promises and weak leadership. it's still about the economy and we're not stupid. by the way, newt gingrich has said if he doesn't win the delaware primary tonight he will reassess his campaign. yes, he is technically still running. >> chuck todd, thanks. >> you got it rjsz a late development out of washington today in the secret service prostitution scandal, more agents are out, two are resigning. two are being cleared of misconduct but will face administrative action. and another will have his security clearance taken away. charles grassley raised a new spector of national security when he told a radio interviewer

"who knows who might be using prostitutes" the russians are famous for that to get information out of us. grassley says he fears this is the tip of the iceberg and wants an outside investigator. a man who was once in john edwa edward's inner circle, a trusted top aide during the '08 presidential campaign is now the star witness against him in his federal trial. andrew young spent a second day on the witness stand for the prosecution, told a story of elaborate deception involving hundreds of thousands of dollars, nbc's lisa myers is with us from the court house in greensboro, north carolina. good evening. >> good evening, brian. this was the government's day through their star witness. prosecutors detailed edwards' affair, the hunt for money to keep his mistress dwi et and claimed the former presidential candidate was deeply involved every step of the way. andrew young, edwards' once

loyal aide arrived ready to tell the jury that while john edwards was on the road campaigning for president, there was a frantic search behind the scenes for money to support real hunter after she threatened to go public with their affair. she had been fired from her job as campaign photographer after elizabeth edwards spotted her in 200 and confronted her husband. young said edwards told him to approach two wealthy friends for funds to help hunter, they turned him down. then they decided to try rachel mell mellon, who provided $725,000 in checks for what she was told was a noncampaign expense. checks written to her decorator and signed over to young's wife. >> if you believe andrew young, then i think the jury will believe that john edwards knew what was happening in terms of the money flow. >> young says five times he

questioned whether the payments were legal. it all just seemed crazy, it looked and smelled wrong. but edwards assured him it was completely legal. in his tell-all book, young said the funds were gifts, entirely proper and not subject to campaign finance laws. but today he appeared to change his tune. saying the money was to influence the outcome of the election. echoing the government's allegations that they were illegal campaign contributions. young is testifying under a government grant of immunity. one of the more electric moments came when young recounted edwards reaction to learning hunter was pregnant. he used a pejorative term and said it was a one in three chance it was his child. >> that's not the type of reaction many of the jurors would feel like they would have had. >> reporter: young also testified that after hunter's pregnancy was reported by a tabloid, edwards begged him to falsely claim paternity of the child, how he didn't want mrs.

edwards to die with this in the papers. elizabeth edwards was battling breast cancer. during young's testimony, edwards clenched his jaw, or jotted notes. his older daughters were in the courtroom but they didn't seem to react. >> lisa myers, thanks. it's been two years since the whole world watched as millions of gallons of crude oil spilled into the gulf of mexico. the justice department has filed the first criminal charges against a former bp engineer who they say destroyed hundreds of text messages about the amount of oil we watched on live television gushing from the ocean floor, including one text message saying too much flow rate, over 15,000 barrels a day. at the time bp was saying the amount was much lower, three times lower than that. bp says it's couldn'ting with this federal investigation.

the news came late today, it sure sounded alarming,ed first confirmed case of mad cow disease in the u.s. in six years. this case in a dairy cow in california. the government says the food supply is safe, but this discovery is raising a lot of questions. our report tonight from our chief science correspondent robert bazell. >> reporter: the cow was found at a recycling plant for dead live stop in hanford, california. it presents no threat to human health. >> this particular animal did not enter the food supply at any time. there's no concern about that. >> reporter: bse, commonly called mad cow disease is a fatal disintegration of the brain and nervous system. it first gained attention in britain in the '80s and '90s, where more than 4.4 million cattle were slaughter to control the outbreak. the disease is usually transmitted by a rare infectious agent called a prion.

cases can appear spontaneously. usually the disease is acquired by eating the tissue of an affected animal. animals had been a common source of food for cows in britain. in britain, 175 people including jonathan sims got a human form of the disease by eating meat from the infected animals. the affected dairy cow does not pose a hazard. there was no mad cow disease detected in the u.s. until 2003, when a cow born in canada was detected in washington state. after that, the u.s. set up a surveillance system, japan and some other countries for a time banned the import of beef. >> this announcement should not disrupt trade, and the reason for that is, the -- we follow international guidelines. >> reporter: including today's finding, u.s. officials have found four cows in the u.s. with with with mad cow disease. in 200, the surveillance program

was cut back because it was finding so few cases. consumer groups are demanding increased surveillance. but the critical take home message is, there is no evidence of any threat to human health. >> the original isolated case. robert bazell, thank you as always. apple reported second quarter earnings today, it was a blockbuster. $11.6 billion in profit. up 94% from the same time last year. much of this increase, they say, came from asia gobbling up iphones and ipads. by the way, they're selling over 8 million iphones per po. apple stocks surged 7%. in after hours trading. the stock went up more than $40 a share. as for the rest of wall street, it was a mixed day, the dow was up more than 74 points. the nasdaq lost almost 9 and the s&p 500 up 5. still ahead as we continue along the way on the front lines, an extraordinary look at an

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working hard to make it better, the city of detroit has seen more of its share of problems in recent years. and the city's fire commissioner came under fire this week for suggesting his department should let abandon eed buildings in th city burn down. it's one challenge faced by detroit's fire department and a lot of it has been captured in a new documentary film. our report tonight from nbc's kevin tibbles.

>> detroit is home to the busiest firefighters in america. >> last year alone, we had over 30,000 actual fires called. i mean, we're in trouble. we need help. >> reporter: the film simply called "burned" documents the lives of the firefighters charged with saving a city many have written off as dead, and they risk their lives doing it. >> there's some buildings that you come out of and you realize that the structure is designed to kill firemen. >> you don't give them the equipment they need and you send them into situations they shouldn't be going into, they can get hurt and killed. it's easy to forget that. >> reporter: a truly american story of hope, courage and camaraderie. in the face of such decline and debt, firefighters can't afford to repair equipment or replace leaky boots. >> i feel like a loser. >> can't seem to get ahead of

it. >> every problem seems to generate another problem, and another problem, and another problem. >> reporter: in 2010, as the filmmakers were working on the documentary, "nightly news" was covering an inferno that wiped out dozens of vacant homes in one abandoned neighborhood. along this street alone, four houses burned before the fire department even got here. the detroit fire department was confronted with 85 buildings burning out of control. >> i'm from detroit, and i never realized how it's not a typical place in terms of fire. you leave detroit and you realize, not everyone is burning their city down. >> reporter: in the motor city, fires, arson fires have become the norm. much of this vivid footage was taken by the firefighters themselves, who wore cameras on their helmets. >> it's not a movie about detroit, it's a movie about the guys that are going to come to your house when it's on fire. >> we need to be there for them,

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look at this latest spectacular display from italy's mount etna. lava spewing over the night sky of sicily. it's been a banner year for the northern lights because of all the solar activity. some fresh solar wined withes made for a spectacular light show over the south shore of lake superior in michigan's u.p. the tiny white spec moving across the lake is a freighter. if these pictures are this great over time lapse. imagine how it must have looked to those on the vessel. two web videos getting heavy circulation right now. the first one could be anyone

walking along using a cell phone. that's a sinkhole. eventually they used a ladder and a rescue squad to successfully get her out. this home video has a lot of people talking these days. he decided to chronicle the growth of his daughter over 12 years. he decided to make a time lapse video of his daughter from infancy through a lot of hairstyles until we see her emerge as a beautiful 12-year-old girl, all in 2:45. the father spoke with us via skype today from his home in the netherlands. >> it appeals to a sort of soul feeling of our lives, with live images. >> the filmmaker along with his subject the entire time lapse

video and more of the interview on our website tonight nbcnightlynews.com. while in north carolina today, the president taped tonight's late night with jimmy fallon for air tonight on nbc at 12:30 eastern time. fallin talked the leader of the free world into a guest role, a recurring built on the show, slow jamming the news, including the issue of student debt. >> we're not friends. >> now is not the time to make school more expensive for our young people. ♪ >> jimmy fallon and the president for tonight's show. up next here tonight, a woman who's in a class of her own, we will meet your teacher of the year. i'm a marathon runner,

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finally tonight, a woman who's being hailed as the best of the best in american classrooms out of more than three million teachers in this country. she was honored today at the white house, as teacher of the year. we get her story tonight as a classroom leader in our education nation. here's nbc's kristen dahlgren.

>> reporter: even outside the classroom, rebecca mieliwocki can teach us a lot. >> i think a great many americans wake up on a monday morning sort of grumpy about what they have to do when they get to work. i wake up excited about what i get to do. >> reporter: that enthusiasm was honored at the highest level. >> there is our 2012 national teacher of the year, rebecca mieliwocki from burbank, california. >> reporter: her students know why she's teacher of the year. >> what makes her a great teach summer. >> she's amazing. she's the best teacher i've ever had. >> reporter: mieliwocki is humbled. >> i'm not the best teacher in america, there isn't one. >> reporter: she loves learning as much as teaching. >> i'm only as good as i am because i walked into other teacher's classrooms. >> reporter: she never loses her sense of humor.

>> i have to say, she was a little goofy when i met her. >> reporter: for the 43-year-old, teaching was in her dna. she tried law school and publishing, but finally she realized this is where she belonged. here in her class, she tries to keep things fun for her student. she plays music, and the bell on her desk always rewards a right answer. >> the kids are like cat nip to cats. they can't wait to get to class. >> reporter: at a time when the education system is under fire and facing cut backs, she knows what's on the line. >> it's very important to me to get this right. the future of our nation depends on how strong the educators are. i feel i need to be the best i can be. >> reporter: she was thinking about her students taking their state tests today. >> i am counting on you, you guys better bring it. you're ready. >> reporter: a long distance lesson in being the best. kristen dahlgren, nbc news,

burbank, california. >> great story to end on as we complete our broadcast for this tuesday night. thank you for being here with us. i'm brian williams, we hope to see you right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com