Can You Get More Than 11 Right on This Football Rules Quiz?

Incomplete passes stop the clock momentarily. This is hugely important in close games when time is running out for the losing team.

The line of scrimmage is where the battle lines are drawn. Before each play, both teams approach the line of scrimmage and remain there until the play begins.

Compared to basketball or soccer, football requires many players. Each side must field 11 players for each play.

Football games are broken into four quarters, and those are divided by one halftime. It is just enough time for players to catch their breaths and evaluate their bruises.

Offensive linemen can't so much as twitch before the ball is snapped. Otherwise, the offense is smacked wth a false start penalty.

Frustrations sometimes boil over and players shove or punch each other. Unnecessary​ roughness results in a 15-yard penalty, so much yardage that it can skew an entire drive.

In the NFL, coaches can contest many aspects of a previous play, such as the spot of the ball or an incomplete pass. To do so, they throw a red challenge flag onto the field.

The sidelines terminate the play. If the player with the ball crosses over the sidelines, he's out of bounds, and the clock stops.

After a touchdown, offenses typically elect to kick a 1-point PAT (point after touchdown). But if the score justifies it, they may run a play in hopes of scoring a two-point conversion, which is harder to accomplish.

Touchdowns are worth 6 points. Teams with high-powered offenses score them in bunches in today's fast-paced game.

After each quarter, the teams switch sides on the field. Depending on the wind and weather, this change of orientation can drastically alter game strategy … and even the game's outcome.

The offense must gain 10 yards, by ground or by air, in order to receive a first down. Some teams are so potent on offense that they repeatedly gain first downs in just one or two tries.

A facemask penalty is called when one player grabs the other's facemask. This move is regarded as particularly dangerous because doing so can cause serious physical harm.

Tackling the ball carrier in his own end zone is called a safety. Not only does the defense receive two points, but the offense has to kick the ball away, often giving the other team very good field position.

The QB, or quarterback, often drops back to throw a pass. If he intentionally throws the ball away to avoid a sack, he's flagged for intentional grounding.

Offenses have four downs to gain the 10 yards necessary for a first down. After third down, they typically elect to try a field goal or try another play. If they don't make a first down on that play, the team must then punt the ball away to the other team.

Teams must be sure that they're ready to attempt field goals. Because if they miss, it means the offense gives up possession of the ball to the other team.

If the fourth quarter ends in a tie, the game goes into overtime. Overtime rules vary depending on whether the game is high school, college or pro.

The football field is neatly divided by lines. At 5-yard intervals, a line stretches across the field, marking the progress (or lack of progress) of the offense.

Because some coaches might be tempted to use challenge flags to slow down the pace of a game, there's a penalty for gratuitously challenging plays -- failed challenges mean your team loses a timeout.

Before each play, the officials must place the ball where the previous play ended. The "spot" of the ball can have a major impact on how the offense approaches the next play.

The NFL tweaked its rules to favor QBs in 2018. Defenders must avoid landing on the QB during a tackle. This ​is to avoid injuring the league's most valuable players.

The hash marks are the short line between the longer lines that stipe the field in five-yard intervals. Before each play, the ball must be placed between the hash marks, giving the offense room to roam from side to side.

NFL rules are moving more toward player safety. If a tackler leads with his helmet, it's an automatic 15-yard penalty, and can also lead to fines and suspensions.

In numerous situations, for instance, the end of the first half, the offense may elect to go a final play. The QB takes the snap and kneels, essentially giving up the play.

The offense obviously loses possession if it fumbles or throws an interception. It also turns over possession after a score, but in a good way -- after all, it means the offense put points on the scoreboard.

In a close game, many teams will elect to try an onside kick during a kickoff. Once the ball has traveled just 10 yards, the kicking team can pounce on it and take possession.

Intentional grounding leaves players and fans pulling out their hair in frustration. Because not only does it result in penalty yardage, but it also causes a loss of one down, which often kills a drive.

In the NFL, pass interference is penalized with 15 yards … or at the spot of the foul, which might be much farther down the field. These penalties can cause serious harm to a defensive stand.

Most plays consume clock time, but a few do not. Point-after attempts, for example, don't take any time off the clock no matter how long they might drag on.

The playing area is 100 yards long. Each end zone is 10 yards long, so altogether, the entire field is 120 yards long.

In the past, the offense had to kick a point after (PAT) after a game-ending score, even if that point had no impact on the outcome on the game. Now, that meaningless PAT is no longer necessary.

High school football games are a bit shorter than college and pro versions. Each quarter is 12 minutes long, as compared to 15 minutes each for the more mature games.

Football fields are of 120 total yards long, including the end zones. They're 53.5 yards wide, enough for players to accelerate to a sprint and turn the corner toward their objectives.

It's a new rule meant to reduce high-speed collisions. In the NFL, the kicking team can no longer take a running start prior to the kick.