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Each learner is randomly assigned their first pre assess question - so the chance the learner can copy one of their peers is dramatically reduced;
We ask at least 2 questions from a layer before we decide the learner has probably mastered the questions in that layer - so the chance of a lucky question distorting our assessment is reduced.
When the teacher looks at the Progress in Topic from plan teach and no longer sees grey blue boxes, then the topic is fully pre assessedSee https://timelypractice.atlassian.net/wiki/spaces/CKB/pages/3110699127/Using+timely+practice#(4)-when-can-the-teacher-begin-to-use-Plan-Teaching-within-the-app%3F for more information - and how the teacher can track the pre assess process.