Welcome back. In the US state of Connecticut, students from Sandy Hook Elementary School are heading back to lessons today in a different building -- three weeks after the massacre that killed 20 of their classmates. The tragedy sparked a national debate on gun control in the US. Meanwhile SOME Americans are rushing to BUY more guns. In December, the FBI performed background checks for nearly 2.8-Mmillion customers at gun stores. That's an increase of 39 percent over November - and a new record.