The series is being cancelled, presumably to make way for a new Avengers kids series.

Source: Marvel Solicitations

Marvel quietly announced that Avengers Academy, written by Christos Gage, has been cancelled, with its final issue being released in November. The series, which spun out of the Age of Heroes was well-received by fans but struggled to sell. Although the series received boosts from tie-ins to Fear Itself and Avengers vs. X-Men, Marvel still decided to end the series, although it's likely that it will be replaced by a new series in December.

In addition, Avengers, New Avengers and Defenders were also cancelled by the publisher, although both Avengers series will be relaunched the following month as part of the Marvel NOW! initiative.

Check out the full solicitations here.