kill two birds with one stone

[kill two birds with one stone] {v. phr.} To succeed in doing twothings by only one action; get two results from one effort.

Motherstopped at the supermarket to buy bread and then went to get Jane atdancing class; she killed two birds with one stone.

The historyteacher told us that making an outline kills two birds with one stone;it makes us study the lesson till we understand it, and it gives usnotes to review before the test.