We may have misinterpreted the SODOTO pattern and consequently designed a Distributed Behavior that tries too hard to distribute checkmarks. We now assert that only the owner of a site can click to make checkmarks for their achievements with one restriction: the teacher must click to confirm before the student can click to acknowledge.
strict digraph { node [style=filled fillcolor=bisque] teacher -> confirm [label=click] student -> confirm [dir=back] student -> ack [label=click] }
A student's plugin will look to the teacher's to see if a step has been confirmed. Only then will the student's checkbox become enabled for clicking. github 
There will be one shallow and narrow path leading through teachers back to the founder of a lesson. That is the count of confirmations for each SODOTO step for all students descended from any student turned teacher.
strict digraph { node [style=filled fillcolor=bisque] 42 -> {12 17 13} [dir=back] 12 -> {3 5 4} [dir=back] 17 -> {6 2 9} [dir=back] 13 -> {7 8 0} [dir=back] 8 [label=6] }
The rolled-up counts might be shown within a teacher's own achievements. Possibly with a save button when counts have changed substantially.
Note that because a teacher need only look at its direct students these students turned teachers can report their counts even while that impact is within a private (login to view) community.