How to read data back from 1)datagrid control 2)Chart Control 3) Pie Chart 4) Line Chart Controls.
Are you referring to a specific Flex in a Week exercise or video?
If you are asking about datagrid, chart, pie & line chart controls in general you should try looking at: http://helpx.adobe.com/flex.html
or contacting Support.
for all dataProvider is common to get / set the list of data.
for example in grid to set dataProvider
var grid.dataProvider=Your Data //ArrayCollection or ArrayList
hope this will help full