2021, Question 2 · Experimental Design · 12 points · about 25 minutes
Rod thickness and breaking force models
Plan an experiment to decide whether the force that breaks a plastic rod depends on its radius or its cross sectional area, sketch both models, then graph given data and pick the better model.
This exam had five free-response questions in 1 hour and 30 minutes: Questions 1, 4 and 5 were short questions worth 7 points each with about 13 minutes suggested, and Questions 2 and 3 were long questions worth 12 points each with about 25 minutes suggested. The current exam has 4 free-response questions in 95 minutes. The skills these questions practice still count.
Lessons this question draws on
1 Read the question
The question is College Board's, from the 2021 exam. It starts on page 6 of the PDF. College Board no longer posts this exam, so it opens from the copy of College Board's PDF that the Internet Archive saved on May 18, 2025.
2 Write your answer
Answer each part the way you would on the exam, in full sentences, with your work shown. Your writing saves as you type.
3 Score it
Score your answer against College Board's scoring guidelines, one point at a time. Give yourself a point only when your answer says what the guideline asks for.
Scoring guidelines (PDF, page 4) What the exam readers saw (Chief Reader report)
Question, scoring guidelines and Chief Reader report: College Board, from the Internet Archive. The title and summary are ours.