Free
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- The Daily, every day
- 36 practice questions a day, each with an explanation: 12 easy, 12 medium, 12 hard
- Full-length Test A and Challenge Test 1
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Digital SAT practice
Reach your peak.
A quick run every day, an explanation for every question, and full-length tests on official timing.
Free, no card. You also get 36 practice questions a day: 12 easy, 12 medium and 12 hard.
The DailySTEP 1
- Three hearts. A miss costs one.
- Streaks pay. ×2 from three in a row, ×3 from six.
- Your longest streak. Beat it tomorrow.
Full-length tests
The real test, rehearsed.
98 questions across four modules, in the digital SAT’s order and on its timing, with a highlighter, a question map and a timer you can see.
How it works
One run a day. One skill at a time.
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1
Play the Daily.
A quick run with three hearts. String right answers together and the questions get harder and the points multiply.
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2
Miss one, learn why.
Every question is tagged by domain and skill, and every answer comes with an explanation.
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Drill that skill.
Practice any single skill at any difficulty, or just the questions you got wrong.
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4
Beat your best.
Come back tomorrow and climb. Progress shows your accuracy and your strongest skills.
Built around the real SAT blueprint.
Every question is tagged by section, domain, skill and difficulty, so you can practice exactly what you need. Full tests run like test day: two Reading & Writing modules, a break, then two Math modules.
Free daily practice
12 easy, 12 medium and 12 hard questions free every day, each with a full explanation. Filter by section, domain, skill and difficulty. Resets at midnight.
Real SAT timing
Take any test on official timing, extended 1.5× time, or untimed to focus purely on accuracy.
Adaptive full-length tests
Four modules in official order. The second module of each section adapts to how you did on the first.
Vocabulary
1,023 essential SAT words. Browse the list, flip flashcards, or quiz yourself.
Your progress
Accuracy across daily practice and full tests, your strongest skills, and the ones that need the most help.
Games
PEAK Survivor, Hole and Peak Defense: three games powered by SAT practice questions.
Explanations
Every answer, explained.
Not just the right letter: how to get there, and why the tempting answer is wrong.
MathProblem-Solving and Data AnalysisHard
A store raises the price of a jacket by 20%. Later, it lowers the new price by 20%. The final price is what percent of the original price?
A80%
B96%Correct
C100%The trap
D104%
Check with $100: $100→then$120→then$96
Turn each change into a multiplier.
Up 20% means × 1.20. Down 20% means × 0.80.
Apply them in order.
1.20 × 0.80 = 0.96
Read the answer.
The final price is 96% of the original. That’s B.
Why not 100%?
The 20% cut is taken from the higher price, so it removes more than the 20% increase added.
Test day
What test day looks like.
Every Peakscor full test follows this order. In the standard tests, the second module of each section adapts to how you did on the first.
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Reading & Writing · Module 1
27 questions32 min
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Reading & Writing · Module 2
27 questions32 min
Adapts to how you did on Module 1. -
Break
10 min
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Math · Module 1
22 questions35 min
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Math · Module 2
22 questions35 min
Adapts to how you did on Module 1.
98 questions · 2 hr 14 min of testing, plus the break
Peakscor by the numbers
- 36free practice questions every day
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Peak
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FAQ
Questions, answered.
The Daily, plus 36 practice questions every day: 12 easy, 12 medium and 12 hard, each with a full explanation. Full-length Test A, Challenge Test 1 and all 1,023 vocabulary words are free too. No card needed.
Pro is $20 a month or $200 a year: unlimited practice with no daily limit, plus every full-length test and Challenge test. Peak is $29 a month or $280 a year: everything in Pro, plus the full Learn course and Peak Plan. Cancel anytime from your account.
98 questions across four modules, in the digital SAT’s order: Reading & Writing Module 1 and Module 2 (27 questions each), a 10-minute break, then Math Module 1 and Module 2 (22 questions each). On official timing that’s 2 hr 14 min of testing. You get estimated section scores and a total at the end.
Yes. In the standard full-length tests, Module 2 of each section is the harder version if you get 60% or more of Module 1 right, and the easier version if you don’t. Challenge tests use the hardest material throughout.
Official timing, extended 1.5× time, or untimed, on every test, including the free ones. Extended time allows 48 minutes for each Reading & Writing module and about 52 for each Math module. Untimed removes the clock so you can focus on accuracy.
A quick run with three hearts. Each right answer builds your streak: the questions get harder as it grows, and your points multiply (×2 from three in a row, ×3 from six). A miss costs a heart and drops you back to easy. Best is your longest streak.
Every day at midnight. You get a fresh 12 easy, 12 medium and 12 hard.
No. Peakscor is an independent SAT practice tool, not affiliated with the College Board. Scores shown are estimates.
Your next point starts today.
Free, no card.
Evaluating statistical claims · Lesson 3
Sampling bias
A sample is biased when the way it was chosen systematically favors some kinds of members of the population over others, so its results lean one way. A biased sample's results can't be generalized to the population. (Sampling two groups at different rates on purpose, then scaling each sample to its own group, is not bias: the difference is accounted for.)
Voluntary response: people decide for themselves whether to take part, as in an online poll, a call-in show or a comment box. People with strong opinions are the most likely to bother, so they are overrepresented.
Convenience sample: researchers use whoever is easiest to reach, such as one class, one hallway or the first 50 people through a door. Those people often share traits that matter to the question.
Undercoverage: the list or place the sample comes from leaves part of the population out. A random sample from that list can't represent the people who aren't on it. Nonresponse: a random sample was chosen, but many of the people picked don't answer. If those who reply differ from those who don't, the results can be biased even though the selection was random.
To decide which way a bias pushes, ask who is overrepresented and how they would likely answer. A survey about how often people eat out, taken at a restaurant, will likely overestimate how often people eat out.
A bigger sample doesn't fix bias. If the way a sample is chosen favors one kind of person, adding more people the same way just adds more of that kind. What makes a sample trustworthy is how it was chosen: at random from a complete list of the population, with most of those selected responding.
Worked example Easy
A sports news website posted a poll asking readers, Should the city spend public money on a new stadium? Of the 2,600 readers who chose to answer, 78% voted yes.
Which statement best explains why the poll's result may not represent the opinion of all the city's residents?
- With only 2,600 responses, the poll is too small to represent all of a city's residents.
- A poll can describe the residents' opinion only if every single resident of the city answers it.
- Sports-site readers who chose to answer may favor a stadium more than residents in general.Answer
- Because 78% is such a large majority, the poll's question must have been worded to push yes votes.
How to solve it
- Ask how the sample was chosen. Readers of a sports site decided for themselves whether to answer: a voluntary response sample.
- Ask who is overrepresented: sports fans, and people who feel strongly about a stadium.
- Those people are likely to favor a stadium more than the city's residents overall, so 78% may overstate support.
Why each choice is right or wrong
- A. Incorrect. 2,600 responses would be plenty if they were a random sample. The problem is how the responses were gathered, not how many there are.
- B. Incorrect. A sample doesn't need everyone. A random sample of residents could represent the city well; this one can't because the readers chose themselves.
- C. Correct. The respondents chose to answer and read a sports website, so sports fans and people with strong views are overrepresented. Their opinions may not match the city's residents in general.
- D. Incorrect. Nothing in the question pushes toward yes; it asks a plain yes-or-no question. A large majority is better explained by who chose to answer.
Worked example Medium
To estimate the average number of hours per week that adults in a town exercise, a researcher interviewed 140 adults as they left the town's largest gym on a Monday evening.
Which statement about the researcher's estimate is most likely true?
- About right, because the researcher interviewed every single adult who walked out of the gym during that time.
- Too low, because the adults interviewed had already finished exercising for that day.
- About right, because 140 adults is a large enough sample to represent a town.
- Too high, because adults leaving a gym likely exercise more than the town's adults overall.Answer
How to solve it
- Ask how the sample was chosen: whoever was leaving one gym at one time, a convenience sample.
- Ask who is overrepresented: people who go to a gym, who likely exercise more than adults in general.
- So the average from this sample is likely higher than the town's true average.
Why each choice is right or wrong
- A. Incorrect. Interviewing everyone at one place is still a convenience sample. Adults who never go to the gym had no chance of being included.
- B. Incorrect. The question is about hours per week, not that day. Having just finished a workout doesn't lower anyone's weekly total; it makes it more likely they exercise often.
- C. Incorrect. Size can't fix how the sample was chosen. 140 gym-goers are still gym-goers, however many are interviewed.
- D. Correct. Everyone interviewed had just been at a gym, so regular exercisers are overrepresented. Their average is likely higher than the average for all the town's adults.
Trap Blaming size instead of selection
When a sample is biased, a wrong choice may say the sample is too small. A biased sample stays biased at any size, and a well-chosen random sample doesn't need to be huge. Ask first how the sample was chosen; only then think about how many.
Trap Random, but from the wrong list
A random selection is only as good as the list it is drawn from. Picking at random from a list that covers only part of the population gives a fair sample of that part, not of everyone. If part of the population isn't on the list, the sample has undercoverage.
Desmos When Desmos isn’t faster
Desmos can't spot bias. These questions ask who had a chance to be in the sample and how they differ from the population, which you answer by reading the setup, not by graphing.
If a question also asks for a percent, such as the percent of a sample that responded, a quick division by hand is enough; Desmos can do it as a calculator if the numbers are awkward.
Practice
Choose a section, then practice a whole domain or drill a single skill.
Full-length tests
Each test mirrors the digital SAT: 98 questions across four modules, 2 hr 14 min on official timing.
A little harder than the real SAT. These tests can run slightly tougher than test day, which makes them good practice: if you can handle these, the real one should feel easier. No question appears in more than one test, Challenge Tests included.
Challenge Tests Hardest of the hardest
Same 98-question format, but every question is drawn from the toughest SAT material: Challenging-tier math throughout and the hardest reading.
Vocab
Study the classic SAT vocabulary list. Browse, flip flashcards, or quiz yourself.
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