(CNN) Chicago teacher LaShonda Carter always told her students she'd be there for them if they needed her.

And she didn't disappoint when one of them reached out, three years after she had been in Carter's class.

Carter was having trouble sleeping one night last week and was browsing through Facebook when she started chatting online with Larresha Plummer, 18.

Plummer told Carter about some rough times she had being going through, and mentioned that she wanted to attend a job fair on Thursday, but had no idea how to get there.

Plummer had just had a baby, and she knew that taking her 3-week-old baby on public transit was a little risky for the infant's health.

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