Using the GDC as an Investigative Tool for IB Maths
Most students use their GDC as a calculator. Top scorers use it as an investigative laboratory — feed it small cases, spot patterns in the table view, then let regression suggest the general form. Paper 3 is where this pays off.
Why it matters
- Every Paper 3 question worth > 3 marks can be attacked from the GDC's table view — generate values, look for constant differences or ratios, conjecture, verify.
- The
SolveN(Casio) andzeros()(TI-Nspire) commands solve unfamiliar equations that would take 10 minutes by hand. - Regression on your own generated data is a legitimate investigative move on Paper 3. If r ≈ 1, your conjectured formula is almost certainly right.
Examiner signals
-
Table explorationFeed un into the sequence / table view. Instantly see the first 20 terms. Constant differences → arithmetic. Constant ratios → geometric. Constant second differences → quadratic. This is 5-10 seconds of work.
-
Regression as investigative logicAfter you generate the small cases, run linear-, quadratic- or exponential-regression on them. If the fit is r > 0.999, quote it as evidence — this is standard IB Paper 3 method language.
-
Numerical solve + verifyNever leave an equation-solving box empty. Even if you can't do it by hand, the GDC will find the roots. Then substitute the answer back to verify — write “LHS = RHS = 12.4” and pick up the A1 mark.
Interactive fluency practice for Using the GDC as an Investigative Tool for IB Maths
A dedicated fluency-first practice set for this skill — thoughtful questions, instant feedback, and worked solutions that build understanding rather than reflexes — is queued up next. Drop your email to be the first to know when it goes live (no spam, one email when it's ready).
FAQ
Which is a better GDC for IB Maths — TI-Nspire or Casio fx-CG50?
Both are IB-approved and both cover 100% of the syllabus. The TI-Nspire CX II has a slightly more powerful CAS-free engine and a cleaner table view. The Casio fx-CG50 is cheaper and faster to boot. Whichever your school issues, the walkthroughs on this site cover both.
Am I allowed to use the GDC on Paper 3?
Yes — Paper 3 (HL only) is a GDC paper by design. In fact, the mark scheme frequently expects you to use it for regression or numerical solving. Papers 2 (both courses) are also GDC-allowed. Only Paper 1 for AA HL and AA SL is no-calculator.
Do I need to show working if I used the GDC?
Always show the model or command. Write “using GDC: LinReg y = 2.93x - 30.5, r = 0.996”. That single line often earns method marks even when the numeric answer at the end is wrong. Silent GDC use scores half.