David Recine

Praxis Core Reading: Key Idea Practice Questions

Praxis Core Reading tests your ability to identify a passage’s key points in a variety of ways. Key idea questions fall under three categories: main theme, primary purpose, and main idea.

Main theme questions are the broadest variety of question. These questions usually open with the words “the passage is primarily concerned with…” This key idea question type asks you only to identify the subject matter of a reading.

Primary purpose questions look at a passage’s central ideas in a bit more detail. These kinds of questions often contain the phrase “the primary purpose of the passage is.…” Here the key idea you must identify is the apparent reason the author chose to write about the main theme. In other words, what is the author saying about the passage’s central topic?

Finally, main idea questions explore key ideas in the most detail, asking about the specific central idea the author uses to frame the topic and serve the purposes of the passage. This kind of question will open with a line such as “which of the following best states the main idea….”

Below are three practice key idea questions for the Core Reading exam, one question for each of the three categories. So that you can clearly see the differences between each type of key idea question, all three questions are based on the same passage.



Twice a year, many Western nations change their clocks in observation of Daylight Savings Time, setting timetables an hour forward in the spring and an hour back in autumn.

The first Daylight Savings Time practices emerged in the early 1900s. However, the origins of this multinational biannual clock change are a bit older. The modern concept of Daylight Savings Time originated more than a century before people first began to actually change their clocks.

Benjamin Franklin, a United States scientist and writer, was the first to suggest seasonal time changes. In a humorous essay that Franklin wrote in 1784, Franklin half-jokingly proposed that clock times in France could be changed so that there was more daylight in the morning, in order to save money on candles for lighting. Decades later, increased use of strict timetables for industrialized life led to a renewed and more serious interest in Franklin’s suggestion.

By the late 1800s, synchronized mechanical clocks and punctual scheduling for transportation and work had become the norm in much of the developed world. After a century of industrialization and increasingly strict consciousness of time, Daylight Savings Time had grown in the imaginations of many authorities in the British Empire. George Hudson, a scientist in New Zealand, wrote the first serious essay proposing the use of Daylight Savings Time in 1895, echoing Franklin by suggesting that such a policy could save money in lighting costs. Within the next twenty years, European industrialists and politicians implemented Hudson’s ideas across the Western world.


Practice question 1: Main theme

This passage is primarily concerned with

A) identifying the authors of famous essays about Daylight Savings Time.

B) describing particular individuals’ thoughts about the management of time in the industrial world.

C) suggesting that all early supporters of Daylights Savings Time were scientists.

D) criticizing the logic of a Daylight Savings Time proposal made by a specific Western thinker.

E) explaining the origins of an international practice that involves changing official clock times.


Practice question 2: Primary purpose

The primary purpose of this passage is to

A) discuss the evolution of a modern time-management policy.

B) imply that Daylight Savings Time is not as common as some people assume.

C) suggest that modern people do not take the idea of Daylights Savings time very seriously.

D) show how national opinions on Daylight Savings Time have changed since the 1800s.

E) contrast serious writings about Daylights Savings Time with satirical ones.


Practice question 3: Main idea

Which of the following best states the main idea of the passage?

A) The idea of Daylights Savings time is older than most people think.

B) The concept of changing clock times twice a year developed slowly as a reaction to industrialization.

C) Both Benjamin Franklin and George Hudson wrote humorously about Daylight Savings Time.

D) The United States and New Zealand had culturally different reasons for changing their clocks.

E) An early rationale for Daylight Savings Time involved saving money on candles.


Answer key

  1. E
  2. A
  3. B



  • David Recine

    David is a Test Prep Expert for Magoosh TOEFL and IELTS. Additionally, he’s helped students with TOEIC, PET, FCE, BULATS, Eiken, SAT, ACT, GRE, and GMAT. David has a BS from the University of Wisconsin-Eau Claire and an MA from the University of Wisconsin-River Falls. His work at Magoosh has been cited in many scholarly articles, his Master’s Thesis is featured on the Reading with Pictures website, and he’s presented at the WITESOL (link to PDF) and NAFSA conferences. David has taught K-12 ESL in South Korea as well as undergraduate English and MBA-level business English at American universities. He has also trained English teachers in America, Italy, and Peru. Come join David and the Magoosh team on Youtube, Facebook, and Instagram, or connect with him via LinkedIn!

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