Desmos is built into the digital SAT, and most students barely use it
Every student sitting the digital SAT has a full Desmos graphing calculator inside the test app, on every maths question, in both modules. Most use it for arithmetic and nothing else.
That is a waste of the single largest change between this test and the paper one. Used properly it removes whole categories of algebra — not by helping you solve them faster, but by letting you not solve them at all.
The principle: stop solving, start looking
Desmos is a graphing tool, and the SAT asks a lot of questions whose answer is a point on a graph wearing a disguise. Any time a question asks where, how many, or for what value, there is usually a version of it you can see rather than solve.
Six places it wins
1. Systems of equations. Type both equations, look at where the lines cross. No substitution, no elimination, no sign errors. This works for nonlinear systems too — a line and a parabola crossing twice is immediately obvious, and finding those points algebraically is a minute of work with two chances to slip.
2. “How many solutions does this system have?” Graph them. Parallel lines never meet, identical lines lie on top of each other, everything else crosses once. A question that tests whether you remember what the discriminant means becomes a question about whether two lines look parallel.
3. Finding the vertex, roots or intercepts of a quadratic. Type it, click the points. Desmos labels them. Completing the square is faster to understand than to do under time pressure.
4. Solving an equation you would rather not rearrange. Anything of the form
f(x) = g(x) can be graphed as two curves; the answer is the crossing point.
This is the one that saves the most time on ugly radical and rational equations,
where the algebra has extraneous-solution traps that a graph simply does not
have.
5. Checking an answer you already have. Faster than redoing the algebra and catches a different class of mistake. If you solved it by hand and the graph disagrees, you have learned something worth knowing before you move on.
6. Statistics questions with a list of numbers. Desmos will take a list and give you the mean and median without arithmetic — useful precisely because those questions are usually testing whether you understand which measure to use, not whether you can add.
Two places it loses
When the question is about structure rather than value. “Which expression is equivalent to…” or “what does the coefficient represent in this context” — graphing tells you nothing, and typing it in costs twenty seconds you will want later.
When you do not already know how you would solve it by hand. Desmos speeds up a student who understands the problem. It does not rescue one who does not, and the time spent typing while hoping something appears is time gone. If you cannot say what you are looking for on the graph, close it.
The part nobody practises
Typing speed. Entering a fraction, an exponent or a square root in Desmos takes a specific sequence of keystrokes, and a student meeting that for the first time on test day will spend thirty seconds on something that should take five.
This is genuinely the whole trick: practise in the real thing. Use the calculator inside Bluebook, on real practice tests, until entering an equation is automatic. Practising algebra on paper and then meeting Desmos cold is the usual reason students report that it “didn’t help” — it did not help because it was unfamiliar, not because it was unhelpful.
A reasonable target
Not every maths question. On a typical module, three or four questions have a faster graphing route, and knowing which ones — quickly, without deliberating — is what separates students who gain time from students who lose it.
That recognition is trainable, and it is one of the things a per-question timing log makes visible: if your slowest correct answers cluster on systems and quadratics, you have found your Desmos list.