Imagine Math's adaptive logic allows for students to 'test out' of lessons. All students are prompted to begin with a Pre Quiz for their upcoming lesson. The default setting in Imagine Math is to allow students who score 80% or higher, the option to skip the lesson. That lesson will then be marked as 'passed' and the student advances to the next lesson's pre-quiz.
Students will work through all lesson activities only if they score lower than 80% on the lesson's pre-quiz. If you wish to require that students NOT be permitted to test out of lessons, then you will need to customize and assign a pathway where the pathway options are set to turn off the Allow Test Out? option.