When defense attorneys quizzed her by putting the name up on a big screen, Alexis said she couldn't read anything.
Alexis' sister-in-law, Nadine Alexis, testified that she had taught her how to read and write Stern's name.
Outside the presence of the jury, the defense accused the prosecution of encouraging Nadine Alexis to lie.
She said she was not coached and added that someone else read the prescription bottle and told Quethlie Alexie what was on it.
Stern, Eroshevich and Dr. Sandeep Kapoor have pleaded not guilty to providing Smith excessive opiates and sedatives. They are not charged with causing her death in 2007.
Nadine Alexis went on to testify that a movie inspired her previous claim that she saw two defendants melt pills in a spoon and inject Smith with the liquid. She said she saw a spoon being taken into a bathroom with Smith but did not see any drugs being melted or injected by Stern or Eroshevich.
"Did you tell police you got the idea of melting pills from a movie you'd seen?" Eroshevich's lawyer Brad Brunon asked.
"Yes," she said. "I saw that on TV."
The defense also showed more photos to jurors. The 92 photos of Smith presented show her seemingly healthy and playing with her baby, embracing her lawyer-boyfriend Stern and going on a fishing trip.
The Associated Press contributed to this report.