Should (do you) add stretch objectives in JIRA sprints?

[arama mihai]

Hi,

Some of our teams use stretch objectives in their sprints and some not. My question is for the teams that do use stretch objectives in their sprints, in JIRA (this is important).

They do the following:

- the stretch items are either taken from the next sprint, or they are taken from a sprint that's never actually started, called "Extra". The team knows that if they finish the items in the current sprint, they can take anything from the "extra" sprint. So "extra" is just a prioritized backlog.

So the sprint is not finished, but the initially planned items are (I assume stretch objectives are not added initially in the sprint, because if they will not be finished the burn-down chart would look horribly).  Now the team takes something from either the next sprint, or the extra sprint.

What happens when they can't actually finish this new item? In JIRA, since it's added to the sprint, it modifies the chart, and at the end, the statistic is affected negatively.

How do you handle (or propose to handle) such cases? 

Thank you!