These problems address prerequisite concepts and skills for the unit. Teachers can use these problems to identify unfinished learning that can be carefully addressed during the unit. 

What if a large number of students can’t do the same pre-unit problem? Teachers are encouraged to address prerequisite skills while continuing to work through on-grade tasks and concepts of each unit, instead of abandoning the current work in favor of material that only addresses prerequisite skills. Look for opportunities within the upcoming unit where the target skill or concept could be addressed in context or with a center. For example, an upcoming activity might require adding or subtracting within 100 to compare length measurements. Some strategies might include:

• ask a student who can add and subtract reliably to present their method
• add additional questions to the warm-up with the purpose of revisiting the skill
• add to the activity launch a few related addition or subtraction problems to solve, before students need to do this in the context of measurement
• pause the class while working on the activity to focus on the portion that requires addition or subtraction

Then, attend carefully to students as they work through the activity. If difficulty persists, add more opportunities to practice arithmetic, by adapting tasks or practice problems, including practice problems from a previous unit.