....and now my attempt at a very brief description of the 3 major task
types in the USA (although diagrams are a lot better than words with
these) -

First rule of sailplane racing: Its all about your average speed.
You're trying to fly as fast as possible, while completing the task
you have been assigned. Another way of saying the same thing is to
say that you want to complete the task in the shortest possible time.
Remember that Speed = Distance / Time. If you take less time (or fly
farther), your average speed goes up. If you take more time to fly a
certain distance, your average speed goes down. Keep this mind, it
will come up later in this post.

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Assigned Task (AT):
-----
Get a list of waypoints. Fly within 1 statute mile of each one of
them, in the right order. Come home safe. Very straightforward, but
inflexible (i.e. if weather changes or if the sailplanes in the
contest have different performance levels).

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Turn Area Task (TAT) or Assigned Area Task (AAT):
-----
Get a list of waypoints. Each waypoint has a cylinder around it, and
each cylinder can have a different size (radius). To complete the
task, or fly into the cylinder surrounding each waypoint, in the
proper order. The trick with a TAT/AAT is that you have a minimum
time. How does this relate to the "average speed" issue I raised at
the beginning of this post? If you come home before the minimum time
elapses, the "unused minutes" are added onto your total time - thereby
lowering your average speed.

To prevent coming home early you must sometimes fly deeper into one or
more of the cylinders (maybe even to a part of a cylinder that's
farthest from all the other waypoints). The bigger cylinders give you
more options on how "deep" to fly and what course to fly (following
cloud-streets, staying away from blue holes, avoiding bad weather,
dodging hostile terrain, etc). Slower pilots or lower-performing
sailplanes can fly the entire task by just touching each cylinder,
faster pilots/sailplanes can fly deep into each cylinder in the same
amount of time - so everyone can complete the task. This allows the
TAT/AAT to accomodate a wide range of pilot skill, sailplane types,
and weather situations.

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Modified Assigned Task (MAT):
-----
Think of this as the "multiple-choice task". It starts off like a TAT/
AAT, but after you fly the required waypoints you have the _option_ of
flying to additional waypoints that you choose (you will have to fill
out a card while you fly or when you land, listing the waypoints that
you are claiming you flew to). The only major restriction is that you
cannot repeat the same two waypoints over and over again - you must
fly to a different waypoint, before circling back to repeat either of
the last two waypoints you've been to. Scoring is similar to a TAT/
AAT, with a minimum time. Strategy can be more complicated than the
other task types, but don't worry about strategy now. Mostly these
tasks tend to be called on marginal days, when the contest staff
aren't sure what the weather is going to be like - although they have
the potential to be used in more interesting ways.

Enjoy,

--Noel