Deal 5 ♠  
 
 
♣  
 
 WEST  NORTH  EAST  SOUTH
1♠2 BID 
 

The bidding has gone as shown.
Decide what you would say, then click on BID above.
  ♠ K 10 9 3
6 4
A 6 4
♣ 10 8 6 3
 

 
Deal 5 ♠ A Q 8 7 6
7 3
K Q J 7
♣ 9 2
 
 WEST  NORTH  EAST  SOUTH
1♠23♠
passpasspass

You would have bid 2♠ if East had not overcalled.

Instead, with 4 trumps you can jump to 3♠ as a preemptive measure. Partner will not mistake this for a limit raise since you would have cue-bid with 11+ points and support.

The jump to 3 is based on the Law of Total Tricks - bidding to a trick level equal to the number of your side's trumps.

 Deal 6 
  ♠ K 10 9 3
6 4
A 6 4
♣ 10 8 6 3