This lesson is primarily directed at the Advanced Placement Computer Science class which is taught using Java. BYOB/Scratch serves as an excellent scaffolding tool to visually represent programming concepts. Non AP classes which use programming concepts such as loops and boolean (true/false) expressions may also make use of this lesson. Students should already be familiar with concepts such as variables and loops. BYOB allows for the creation of several types of custom built code blocks. A predicate block is used to create boolean expressions.