Mark Memmott

Good morning.

Our early headlines:

-- Tens Of Thousands Expected Today At Florida Rally For Trayvon Martin .

-- The Arguments Begin: Supreme Court Takes Up Health Care Starting Today.

A rally in Sanford, Fla., today "to demand justice in the Trayvon Martin shooting death," is expected to draw "tens of thousands of people," Orlando's WFTV says.

The rally — one month after the black teen's death — is due to begin at 4 p.m. ET and end with those thousands gathered outside the city's civic center as the Sanford City Commission meets to hear from the 17-year-old Martin's parents.

NPR's Ken Rudin is a fan of using history as a guide to what might happen next when it comes to politics, and this morning he focuses on the 2012 race for the Republican presidential nomination and what lessons we might learn from an earlier battle between GOP contenders.

"A house fire believed to be the worst in Charleston's history claimed its ninth victim Sunday," West Virginia's Sunday Gazette-Mail reports.

According to the newspaper, 7-year-old Bryan Timothy Camp was taken off life support Sunday morning. The fire at the home he lived in with his mother, her boyfriend, an aunt and six other children began around 3:25 a.m. ET on Saturday. Only the aunt survived. The Gazette-Mail says the rental home had no working smoke detectors.

Here's how we'll be following the Supreme Court's three days of oral arguments about the President Obama's health care overhaul law, which as we've previously noted begin today.

As we always try to do when major stories are developing, we'll watch for key moments and pass along the news as soon as possible.

Saying that her husband "loves children, he's like a big kid himself," the wife of the U.S. Army soldier accused of killing 17 Afghan civilians on March 11 has told NBC News that the accusations against Staff Sgt. Robert Bales are "unbelievable to me."

"I have no idea what happened, but he would not ... he loves children, and he would not do that," said Karilyn Bales.

Three straight days of oral arguments about the constitutionality of President Obama's health care overhaul law start Monday at the U.S. Supreme Court.

It's a perfect political storm: an issue that affects everyone and has deeply divided the major political parties coming before the nine justices smack in the middle of a presidential campaign.

Much is riding on what the justices decide. Their rulings are expected by the end of June.

Army Staff Sgt. Robert Bales has been officially been charged with 17 counts of premeditated murder for the March 11 killings of unarmed men, women and children in Southern Afghanistan, The Associated Press just reported from Kabul.

It adds that "premeditated murder is a capital offense and if convicted, Bales could be sentenced to death."

Martin Killgallon, marketing director for Ohio Arts, we salute you:

"We have a left knob and a right knob," he said of his company's Etch A Sketch, The Associated Press reports, "so we neutrally speak to both parties."

There's a new explanation for why the citizens of Clintonville, Wis., have been hearing booms this week:

There was a 0.9 percent drop in sales of existing homes in February from January, the National Association of Realtors reports. But, at an annualized rate of 4.59 million they were still up 8.8 percent from February 2011.

"The market is trending up unevenly," NAR chief economist Lawarence Yun concludes in a statement from the association.

Update at 10:12 a.m. ET. It's Official:

"It's time for a development professional to lead the world's largest development agency," President Obama just said as he announced he is nominating Dartmouth College President Jim Yong Kim to head the World Bank.

Our original post:

"President Barack Obama will nominate Dartmouth College President Jim Yong Kim to head the World Bank," The Associated Press reports, citing "senior administration officials" as its sources.

Along with the word that U.S. Army Staff Sgt. Robert Bales will be formally charged with murder today for the deaths of unarmed Afghan men, women and children on March 11, was the news that the death toll had grown to 17. Until Thursday afternoon, U.S. military officials had consistently said that 16 people were killed.

As The Associated Press has reported, officials made the change without offering a public explanation for it.

Tough defense by Louisville led to the defeat Thursday night of Michigan State in the NCAA men's basketball tournament, NPR's Mike Pesca said earlier on Morning Edition.

The Spartans, who lost to Louisville 57-44, are the first of the four No. 1 regional seeds to be sent home.

Syracuse, another No. 1 seed, managed to hang on with a 64-63 win over Wisconsin. In Thursday's other two games, Florida beat Marquette 68-58 and Ohio State thumped Cincinnati, 81-66.