Update!
Answer: As you may
know, the infield fly rule is designed to protect base runners on first
and second or first, second and third from being forced out on a fly
ball that, in the opinion of the umpire can be caught, but is dropped
intentionally or otherwise by the infielder with less than two outs. In
effect, the infield fly rule says to the runners that they do not have to
run, even if the ball drops in, because the batter is declared
automatically out. Runners may advance at their own risk (i.e. if a
runner(s) runs on a fly ball that is judged to be an infield fly), and the
infielder intentionally drops the ball, the runner can advance. This is
because the ball remains in play when the infield fly rule is called.
I hope this helps. I have included below the specific infield fly rule
from the official baseball rule book for your information.
As for what to tell your 7-8 year old
kids, I would try to explain that the rule is there to keep them from
being put out unnecessarily in the event a fielder tries to fool or trick
them. Young players should understand that as base runners, they do not
try to advance on fly balls before the ball is caught if there is less
than 2 out. If it is a fly ball in the infield, the kids should stay close
to their base and look to the umpire to see if he calls "Infield
Fly!" If the umpire calls it an infield fly, players should
understand that they are not forced to run if the fielder drops the ball.
This is usually were the kids get confused - they know they shouldn't
advance on a fly ball but when it drops they become confused and think
they are forced to run. They are not forced, the infield fly rule protects
them by allowing them to stay on their original base because the batter is
out and not entitled to first base.
By the way... remind them that the infield
fly rule only applies if there are runners on first AND second or
first, second and third. If there is just a runner on first base
only an infielder can drop a fly ball and force the base runner (the
infield fly rule is not in effect).
I would be interested in hearing what
conflicting information you may have heard about the infield fly rule.
Please let me know if you need a better
explanation or additional information.
An INFIELD FLY is a fair fly ball
(not including a line drive nor an attempted bunt) which can be caught
by an infielder with ordinary effort, when first and second, or first,
second and third bases are occupied, before two are out. The pitcher,
catcher and any outfielder who stations himself in the infield on the
play shall be considered infielders for the purpose of this rule. When
it seems apparent that a batted ball will be an Infield Fly, the umpire
shall immediately declare "Infield Fly" for the benefit of the
runners. If the ball is near the baselines, the umpire shall declare
"Infield Fly, if Fair." The ball is alive and runners may
advance at the risk of the ball being caught, or retouch and advance
after the ball is touched, the same as on any fly ball. If the hit
becomes a foul ball, it is treated the same as any foul. If a declared
Infield Fly is allowed to fall untouched to the ground, and bounces foul
before passing first or third base, it is a foul ball. If a declared
Infield Fly falls untouched to the ground outside the baseline, and
bounces fair before passing first or third base, it is an Infield Fly.
On the infield fly rule the umpire is to rule whether the ball could
ordinarily have been handled by an infielder not by some arbitrary
limitation such as the grass, or the base lines. The umpire must rule
also that a ball is an infield fly, even if handled by an outfielder,
if, in the umpire's judgment, the ball could have been as easily handled
by an infielder. The infield fly is in no sense to be considered an
appeal play. The umpire's judgment must govern, and the decision should
be made immediately. When an infield fly rule is called, runners may
advance at their own risk. If on an infield fly rule, the infielder
intentionally drops a fair ball, the ball remains in play despite the
provisions of Rule 6.05 (L). The infield fly rule takes precedence.
(Rule 6.05 declares the batter to be out if he hits what is judged, by
the umpire, to be a catchable fly ball.)
Taken from http://www.mlb.com/NASApp/mlb/mlb/baseball_basics/mlb_basics_define_terms.jsp.
February, 2003