A look at the rules in some Olympic sports
A look at the rules and scoring for some Olympic sports:
Grab your calculator or a good eraser. Modern pentathlon is five sports in one, and it takes as much skill to keep up with the scoring as the athletes themselves.
The Olympic competition features a fencing match, a 200-meter swim, show jumping and a 3,000-meter run combined with three shooting series, and athletes earn points based on their results. For fencing, an athlete gets 1,000 points for winning 70 percent of his or her bouts - that's 25 at the Olympics - and plus or minus 24 points for every additional victory or loss. Win all your bouts, that's 1,240 points. Lose and, well, you get nothing.
The benchmark time in the swim is 2 minutes, 30 seconds, and is worth 1,000 points. Every 0.33 seconds faster or slower - not .34, not .32 - is worth plus or minus four points. And yes, there will be an electronic timing device measuring to 1/100 seconds in London to keep track of every portion of every second.
Athletes start with 1,200 points in the show jumping competition, which takes place on a 400-meter track with 15 obstacles, including at least one double and one triple. There's a deduction of 40 points any time a rider falls, 40 points if the horse refuses to jump, 28 points for a knockdown and four points for every second over the time limit. As if that's not enough, these are random horses, assigned a mere 20 minutes before the show jumping portion begins.
Last up is the run-shoot - or, more accurately, shoot-run since athletes have to shoot five targets before running 1,000 meters, shoot another five targets, run another 1,000 meters, shoot five more targets and run another 1,000 meters. Completing the course in 12 minutes, 30 seconds is worth 2,000 points, with four points added or subtracted for each second faster or slower.
Add the points together, and the one who has the most gets the gold medal. Expect to see scores around 5,500 for the medalists in both the men's and women's competitions.
Boats race backward in six lanes along a 2,000-meter course. The first one across the line wins.
Crews will compete first in heats, with the best boats going through to the next round. For the boats that do not qualify, there is a second chance in the repechage round.
There are 14 different disciplines - eight for men and six for women - ranging across singles, pairs, fours and eights, and over heavyweight and lightweight divisions.
Competition in nine of the 10 classes - men's double-handed Star, men's and women's double-handed 470, men's double-handed 49er, men's single-handed Finn, men's single-handed Laser, women's single-handed Laser Radial and men's and women's windsurfing - is in fleet racing on a low-points scoring system, meaning the boat that has the fewest points at the end of the competition wins.
Each class is scheduled to sail 10 races except the 49er, which will sail 15. Sailors are allowed to toss out their worst score from the first 10 races, or 15 in the 49er class. The 10 boats with the lowest scores compete in the medal race. Points in the medal race cannot be excluded and are worth double.
The women's triple-handed keelboat class will be sailed in a match-racing format in which 12 teams compete in a round-robin format. The winner of each match scores one point while the loser gets zero. The top eight crews go through to a knockout series that will result in a semifinal and then the final. There also will be a petit-final to decide the bronze medal and a sail-off for fifth through eighth place.
There are three shooting disciplines: Rifle, pistol and shotgun.
In rifle events, eight competitors qualify for the final round, where the highest possible score for a shot is 10.9. The final-round scores are added to qualifying scores. In air rifle, men fire 60 shots in qualifying and women fire 40. The final round consists of 10 shots. In men's 50m prone, shooters fire 60 shots in qualifying and 10 in the final round. In three-position rifle, the men take 40 shots each from prone, standing and kneeling positions in qualifying. The women take 20 shots from each position. In the three-position final, shooters fire 10 shots from the standing position.
Pistol events are scored much the same, although in the men's rapid fire pistol, only six qualify for the final round. In men's 50m pistol and 10m air pistol, shooters fire 60 qualifying shots and 10 shots in the final round. In women's 10m air pistol, they fire 40 shots in qualifying and 10 in the final round. In men's rapid fire, they complete two stages of 30 shots each in qualifying. In the final there are eight series of five shots each, with the lowest scorer eliminated from the fourth series on until a last-series, two-man shoot-off for gold. In women's pistol, they use rapid fire qualifying but a 20-shot final.
In shotgun events, shooters aim at clay targets released into the air on the shooter's call. The top six advance to the final. In men's trap and skeet, shooters fire at 125 targets during qualifying, then 25 in the final. Scores from the final and qualifying are added. In women's trap and skeet, shooters compete in a 75-target qualifying round and a 25-target final. In double trap, shooters fire at 150 targets in qualifying and 50 in the final.
Shoot-offs break ties in all finals.
It's all about how fast you swim against the clock. The events begin with preliminary heats and the swimmers with the best times advance to the semifinal round. This format continues until the finals, during which the top eight swimmers race to the finish line.
Lane assignments in the finals are based on the swimmers' times from the previous heats. The middle lanes in the pool go to the swimmers with the quickest qualifying times, which many consider an advantage because it allows them to see how fast their competitors are swimming.
In the relays and distance events, the eight fastest teams or individuals in the preliminaries advance directly to the finals.
Only two swimmers per country are allowed to compete in individual events. Some countries might not have any entries in some events or only one entry, based on how many of their swimmers met Olympic qualifying times. Each country that qualifies a relay can enter one team; the swimmers on the relay might change between the heats and the finals.
Each heat has a maximum of eight swimmers, but there are multiple heats for every event.
Finish times are taken to the hundredth of a second. Because of this, ties can and do occur if multiple swimmers finish a race with identical times. If a tie occurs in a preliminary (a tie for 16th) or semifinal (a tie for 8th) that would cause more than the appropriate number of swimmers to advance to the next round, a swim-off occurs between the tied swimmers.
There are two types of relays - freestyle and medley. The medley relay has each swimmer performing one of the strokes in order of backstroke, breaststroke, butterfly and freestyle. The relays begin the same way as individual races, with the swimmer on the starting block or in the water (backstroker in the medley relay). The subsequent swimmers all start from the block and may be moving. For a start to be legal, some portion of the swimmer must be contacting the block when the swimmer in the water touches the wall. The automatic timing system judges this, with a tolerance of .04 seconds.
The pool is 50 meters long, at least 25 meters wide and at least 2 meters deep so waves won't bounce off the bottom and interfere with the swimmers. There are eight lanes, 2 1/2 meters wide. The depth, lane lines, gutters, walls and circulation system are designed to minimize waves and turbulence.
The pool's automatic timing system is triggered when the electronic signal is initiated (swimmers hear a beep) and stopped when the swimmer touches the wall pad in their lane.
To keep backstrokers from hitting the wall on their turns and finishes, a string of flags is suspended above the water 5 meters from the end of the pool. The lane lines also change color at the 5-meter mark.
Swimmers wear suits closely regulated by world governing body FINA and must be pre-approved months before the Olympics.
A false start results in disqualification.