Scrum Forum

What kind of questions are they trying to answer? 

Working software is always a great measure of progress though. 

How does your Development Team feel about showing their burn-down and velocity to upper management, and how might this impact those metrics? 

Might they be more interested in understanding the return on investment they are getting? The product's value? Ability to innovate? Customer feedback? Quality? Lead time, from concept to cash?

Here is a better place to start: https://www.scrum.org/resources/evidence-based-management

What are Best reports to show progress to upper management.?

A list of the organizational impediments to agile practice which only they are currently in a position to resolve.

+1 @Ian Mitchell!!!!!

As @Tony Divel pointed out you need to know what questions they are asking in order to determine what to show. But always lean towards showing what working software increments have been delivered or are ready to be delivered to the stakeholders.  How those increments are built isn't relevant to upper management. The value is what is important.  Burn down charts of estimated work is meaningless to anyone other than the people actually doing the work. 

If this is a non-negotiable situation where management does not care about Scrum and just wants status, I would say that tracking story points completed would be a good measure. I have seen PMOs use this data to predict how long it will take to get work done for a customer.

Thanks you all for your expert advise. what I learnt In a nutshell : 

1) Velocity as it will help in forecasting 

2) Any report that help them understand impediment where they can help. 

3) working software

agree with Tony, ask them what they are trying to answer.

Some management think that when they switch to agile, outcome or output is faster but it is not. I usually here that when they are using waterfall and project is about to fail, they switch to agile. It will still fail, agile or scrum is not a magic wand.