11. A non-transitory computer storage medium storing executable code, wherein the executable code configures a computing system to perform a process comprising: establishing a content presentation session, wherein individual portions of a content item are provided to each of a plurality of user devices concurrently during the content presentation session, and wherein the plurality of user devices are permitted to submit annotations concurrently during the content presentation session; receiving, from a first user device of the plurality of user devices, an annotation associated with the content item; determining a target amount of annotation content per unit of time to be distributed to individual user devices of the plurality of user devices; selecting a first subset of the plurality of user devices based at least partly on a quantity of the plurality of user devices and the target amount of annotation content per unit of time; transmitting the annotation to the first subset of the plurality of user devices; receiving moderation information regarding the annotation from at least a portion of the first subset of the plurality of user devices; determining that the moderation information satisfies a moderation criterion; and transmitting a plurality of annotations associated with the content item to a second subset of the plurality of user devices, wherein the plurality of annotations includes the annotation.
11. A non-transitory computer storage medium storing executable code, wherein the executable code configures a computing system to perform a process comprising: establishing a content presentation session, wherein individual portions of a content item are provided to each of a plurality of user devices concurrently during the content presentation session, and wherein the plurality of user devices are permitted to submit annotations concurrently during the content presentation session; receiving, from a first user device of the plurality of user devices, an annotation associated with the content item; determining a target amount of annotation content per unit of time to be distributed to individual user devices of the plurality of user devices; selecting a first subset of the plurality of user devices based at least partly on a quantity of the plurality of user devices and the target amount of annotation content per unit of time; transmitting the annotation to the first subset of the plurality of user devices; receiving moderation information regarding the annotation from at least a portion of the first subset of the plurality of user devices; determining that the moderation information satisfies a moderation criterion; and transmitting a plurality of annotations associated with the content item to a second subset of the plurality of user devices, wherein the plurality of annotations includes the annotation. 14. The non-transitory computer storage medium of claim 11 , wherein the process further comprises: determining that the annotation comprises a question; and transmitting, to the second subset of the plurality of user devices, information indicating that the annotation is to be displayed using a different display configuration than at least a portion of other annotations in the group of annotations.