also: read option · the read
Inside zone with one defender deliberately left unblocked and the quarterback deciding, after the snap, whether to hand off or keep based on what that defender does.
The line runs inside zone and deliberately does not block one defender, normally the backside end. The quarterback puts the ball in the back's belly and watches that defender. If the defender chases the back, the quarterback pulls the ball and runs where he vacated. If the defender stays home, the quarterback hands off.
The idea underneath is the same one as an iso, reversed: rather than block a man, you make his decision wrong whichever way he goes. That is worth stating plainly because it is why the play does not need to block him at all. It is what a coach means by saying the read "blocks" a defender.
One decision, one named defender, post-snap. That is a much smaller ask of a quarterback than a full-field progression and a much bigger one than a Wing-T handoff.
read optionRPO, speed option, split zone and siftZone read and RPO are constantly used as though interchangeable and are not. The zone read chooses between two RUNS. An RPO chooses between a run and a PASS. The mechanics look similar at the mesh point and the consequences of being wrong are completely different.
The decision load is one read against one named defender, which is why this play reached youth football faster than any other post-snap read. It still asks a young quarterback to take a hit, which is the real limiter rather than the read itself.