Before bidding to slam (small slam = 6 level, 12 tricks, grand slam = 7 level, 13), the partnership needs to have three requirements satisfied:
• enough combined strength; approx 33 points for small slam, 37 for grand slam
• a suitable denomination to play it in
• enough controls
Using the combined strength of the hands to determine the appropriate level is referred to as quantitative bidding, and allows the partnership to have slam-invitational auctions eg: Partner opens 1NT on ♠QT4 ♥AQ63 ♦KJ52 ♣K7, and you hold ♠KJ7 ♥KJ5 ♦QT8 ♣AQJ2.
West’s 1NT shows 15-17 pts, and East holds 17. So the partnership has 32 to 34 pts. That’s enough for slam if West has 16 or 17 points, but not enough if only 15 points. East offers an invitation to slam by bidding one level beyond game - a quantitative raise to 4NT. With only 15 pts, West declines the invitation by passing.
Trump Fit and Controls
First, look for the best trump fit, next, check for controls.
• A control is a holding that prevents the opponents from taking too many tricks in a suit
• The ace is a first-round control, as it stops the opponents taking the first trick
• In trumps, a void is also a first-round control
• A king is a second-round control. The opponents can take the first trick, but not the second.
• In trumps, a singleton is a second-round control
To bid a small slam, you need first round control of three suits, and second of the fourth. How does the partnership discover whether there are enough controls to make slam? That’s where Blackwood comes in.
The Blackwood Convention
After a trump suit has been agreed, 4NT asks partner how many aces they hold.
5 ♣ No aces (or all four aces. This is rare, so assume none).
5 ♦ One ace
5 ♥ Two aces
5 ♠ Three aces
If the partnership holds all the aces, 5NT now asks about kings.
6 ♣ No kings
6 ♦ One king
6 ♥ Two kings
6 ♠ Three kings
Then make the decision to bid small or grand slam!