Unit 3 Lesson 1 Trace Table page starts with this statement:
In Unit 3, we learned how you can make a trace table that follows the execution of a program.
But the Trace Tables page is the first time students are seeing a trace table. Perhaps one used to be in Unit 2 showing function control flow, but I could not find a trace table prior to the Unit 3 Lesson 1 Trace Table page.