Public Practice Guide
Use this guide to see the type of reasoning MathRoutine expects for grade 12 related rates word problems. The goal is not worksheet volume; it is helping students read the situation, choose a model, and explain why the answer fits.
What Students Practice
Reasoning Patterns
Sample Problems
These grade-specific examples show the kind of student-visible reasoning MathRoutine is designed to support: identifying the important quantities, choosing the right structure, and checking the final answer against the story.
A circular spill has area A = pi r^2. At the moment r = 6, the radius is increasing at 0.4 ft/s. How fast is the area changing?
Reasoning Strategy
Differentiate with respect to time, then substitute the moment values.
AI Support Preview
Keep dA/dt and dr/dt visible through the chain rule.
A position model has derivative v(t) = 6t + 5. What instantaneous velocity occurs at t = 4?
Reasoning Strategy
Evaluate the derivative at the requested time.
AI Support Preview
Clarify that velocity is the derivative, not the original position value.
A rate changes linearly from 8 to 20 over 3 hours. What accumulation is represented?
Reasoning Strategy
Use the trapezoid area: average endpoint rate times width.
AI Support Preview
Prevent using only the left endpoint rate.
A tank starts with 40 units. Inflow is 9 units per hour and outflow is 4 units per hour for 6 hours. What final amount is predicted?
Reasoning Strategy
Find the net rate, accumulate it over time, then add the initial amount.
AI Support Preview
Label inflow and outflow before subtracting.
A circular spill has A = pi r^2. At r = 5 ft, dr/dt = 0.6 ft/s. How fast is the area changing?
Answer
6pi ft^2/s
Reasoning Strategy
Differentiate with respect to time: dA/dt = 2pi r dr/dt.
AI Support Preview
Keep dA/dt and dr/dt visible through the chain rule.
A velocity graph has signed areas 12, -5, and 18 over three intervals. If position starts at 40, what is the final position?
Answer
65
Reasoning Strategy
Add signed areas to the initial position.
AI Support Preview
Distinguish net change from total distance.
A function has f'(x) changing from positive to negative at x = 3. What does that indicate?
Answer
A local maximum at x = 3
Reasoning Strategy
Interpret the derivative sign change.
AI Support Preview
Connect increasing-then-decreasing behavior to a maximum.
Keep Practicing
Practice 1000+ more problems with grade-fit AI support.
Practice Ladder
Modeled after Algebra 1/Algebra 2 workbook expectations: interpret a function or equation in context, solve or compare it, then justify the meaning of the answer.
Translate the language into a mathematical relationship.
Solve while tracking constraints, units, and intermediate quantities.
Check whether the solution makes sense in the original context.
Assessment Signals
A guide is useful only if it clarifies what teachers and parents should look for in student work. MathRoutine tracks these signals during practice instead of treating every miss as the same mistake.
Common Mistakes
Learning Loop
A strong word problem platform should not only say right or wrong. It should notice the pattern: missed unit rate, ignored leftover, reversed comparison, wrong base percent, or equation setup error.
1
Attempt
2
Diagnosis
3
Next practice
Diagnosis Examples
Each word problem should create evidence about setup, calculation, vocabulary, hidden quantities, or final-question confusion. These examples show what MathRoutine is designed to separate after an attempt.
If the attempt shows
The student substitutes values before differentiating.
Likely diagnosis
Related-rate structure is being collapsed into arithmetic.
Next practice
Use rate problems that require writing the differentiated relationship first.
If the attempt shows
The student uses total geometric area when signed net change is required.
Likely diagnosis
Accumulation and total distance are being confused.
Next practice
Practice signed-area stories with endpoint value comparisons.
Practice By Difficulty
Each level shows the reasoning load that level should demand, not just more of the same problem.
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