Isabella and Duncan (along with Gwen (MB), Trent, Dawn and Diego) recycle for a recycling group. Also, Isabella tells Duncan he has to sing "Reduce, Reuse and Recycle" and comforts him a little bit when he cries.
Isabella has her arm over Duncan's shoulder, which Courtney sees. Later, Isabella tells Courtney that she likes Duncan, but only as a friend.
When Isabella hears about Gwen and Vanessa's fight, she spreads the word, and tells Duncan second (she told Phineas first). Later, at the fight, Isabella and Duncan can be seen sitting next to each other.
Duncan and Isabella work together in the sing-off. Afterwards, Duncan apologizes to Isabella for losing them the contest, and Isabella forgives him.
Isabella is saddened when she heard that Duncan was moving, only to be cheered up by Phineas.
Duncan and Isabella high-five when Teresa's plan works.
Isabella wishes Duncan good-luck.
Duncan and Isabella shake hands and make up for their argument.
Isabella wished Duncan was in the film.
Duncan comforts Isabella when she gets scared.
Duncan is impressed when Isabella wins the Pokemon battle against Numbuh Four.
Duncan isn't happy when Isabella and Heather are trapped in Hoenn, and eventually rescues them when they're done singing.
Duncan seems happy when he learns that Isabella was competing.
Isabella seems upset when neither Duncan or Phineas is on her team.
Duncan slaps Isabella when she says she's glad that Courtney's not helping.
Isabella and Duncan argue about whose plan to get inside would work, but later they make up for their bickering.