JACKSON LEADS POP SINGLES BREAKING INTO THE TOP 40.(ENTERTAINMENT)

Byline: JAN DEKNOCK Knight-Ridder

In most chart weeks, it is big news when a song is able to blast into the Top 40 on the pop singles list in its first week on the charts. When four songs achieve the same feat in the same week, it's phenomenal.

Tops among the record-setting bunch, of course, is Michael Jackson's double-sided release of ``Scream'' (a duet with sister Janet) and ``Childhood'' (his theme from the movie ``Free Willy 2''), which as expected set off more than a few chart fireworks this week.

On the pop singles list, ``Scream''/``Childhood'' scored a No. 5 debut,making it the highest debut in the history of the chart. (The previous …