Taking heed; giving close and thoughtful attention(adjective)
Paying particular notice (as to children or helpless people)(noun)
WordNet. Princeton University. 2010.
Use "paying attention" in a sentence
"Mr. Schrupe had said he would be testing us tomorrow, and I had a bad habit of not paying attention in his class when he talked."
"But although we intuitively know that paying attention is the ultimate parenting tool, we underutilize it."
"Before his death in 2004 Pete Knight extrapolated: I think it was a lax condition, not doing something wrong, but not paying attention to what was going on."