This is an open-ended task with multiple possible solutions.
There is full alignment to depth and breadth of standards tagged
There are clear learning objectives that are achievable through completion of the activtites in the lesson
There is an assessment piece included that will measure student progress toward mastery of the specified standard
Strengths: multiple possible solutions; examples of student responses included; additional extension activities included

As an EC teacher, I love how open ended this activity is, even if you do set some parameters (such as a specific number range), it can still be open ended. This activity is fully aligned to depth and breadth of standard tagged. It has clear learning objectives that are achievable through completion of this resource. It also includes clear and sufficient assessment strategies that will accurately measure student progress and mastery of the specified standard. This activity is highly engaging as it promotes critical thinking skills and collaboration among classmates as they try to discover the mystery number. The content is also accurate as it is free of errors and biases. This activity lacks technological elements, but could be easily incorporated with free online math manipulatives.