Think Pair Share Questions

This technique, introduced by Lyman in 1981 (Lyman, F. “The Responsive Classroom Discussion: The Inclusion of All Students.” Mainstreaming Digest, University of Maryland, College Park, MD.) and popularized within the physics community by Eric Mazur in his book Peer Instruction (1997. Upper Saddle River NJ: Prentice Hall), provides an additional layer of structure beyond simple questioning and takes advantage of the power of discussion for making meaning. A question is posed by the lecturer. The students are then asked to think quietly about a question related to material that has just been discussed and commit to an answer. They might share this answer with the lecturer by using clickers or other anonymous devices.

You then ask the students to discuss their answer (and their reasoning) with their neighbors. It is during this time that open critique allows for students to come to a more sophisticated understanding. Students are able to convey information to one another in a way that is more meaningful to other students.

The hope for this website is that GSIs can submit their own TPS questions for Alex while at the same time make comments and edit TPS that have been used in the past and have been submitted by other students. This is entirely optional, but serves as great practice for writing exam questions and questions that involve critical thinking. The hope is that all GSIs, the Head GSI, and occasionally Alex will make comments and improvements on the questions, forming the foundation for a database of TPS questions that will follow this course to the end of time.

An ideal TPS question session would go as follows:

1. The lecture poses a question with four possible answers. None of the answers are immediate throw-aways, that is, obviously wrong.
2. The students think quietly and then give a response. The response is usually done by having them hold up a piece of paper of a certain color.
3. The question is hard enough so there is not an overwhelming majority of the correct answer (say >10% incorrect). The lecturer then asks the students to pair with their neighbors and discuss the question.
4. The second session of responses should have a higher percentage of correct answers.

Things that can prevent TPS from being successful:

1. The question is too easy, or the wording of the responses makes it clear which are incorrect.
2. TPS is not implemented seriously, and students being to lose interest and do not care.
3. The question is too hard and the less than 30% of the class gets it right on the first try.
4. The lecturer has taught 'to' the question, knowing it would eventually be asked and wanted to make sure the students knew exactly what they needed to know.
5. The question involves complicated calculations that cannot be done easily in the students' heads.
6. The question only requires that the students regurgitate information they just heard in the lecture (i.e., No actual thinking is involved).
7. The question is too long, requiring the students to retain too much in their heads when deciding on an answer.

For now, we will have all the TPS on this page. If it grows big enough, we will separate the TPS questions into different pages by topic.

The procedure is as follows:

1. At the top of the Wiki page, click “Edit this page.” (You will have to log in.)
2. Copy the following template (everything between 'Beginning of Template' and 'End of Template'):

(Beginning of Template)

Current Version:

Type your TPS question here

• Response 1
• Response 2
• Response 3
• Response 4

Original Version:

Type your TPS question here

• Response 1
• Response 2
• Response 3
• Response 4

Editing Comments

Explain the changes you made and why you made them. You MUST add your signature to the end of the comment. — Aaron Lee 2009/09/04 01:45

(End of Template)

1. Paste this under the current list of TPS questions.
2. Fill out the TPS question title, creator, and topics. Type your TPS twice, once as the “Current version” and once as the “Original Version.” Leave the commenting part alone (unless you want to make comments on your own question).
3. Save the page.

Everyone is encouraged to make comments on everyone else's TPS questions. Constructive criticism please! Do this by the following:

1. Edit the page the TPS question is located on.
2. Scroll down to the 'Comment' section of that question.
3. If you are making corrections or changes to the TPS question, makes the changes only to the 'Current Version' form of the question. Do not touch the 'Original Version.'
4. If you make changes, you must provide justification in the comments section.
   1. Type your comments underneath the last comment posted. If you are the first, replace the italicized part with your comments. (If you are making drastic changes, you might copy both the old and new versions in your comment, in case we want to revert back.)
   2. At the end of the comment, add your signature. Do this by clicking the button farthest to the right on the toolbar above the editing window.

Current Version:

In your scale model of the Earth and the Moon, the Earth is represented by a baseball. If instead you represented the Moon by a baseball, then

• both the distance separating the model Earth and Moon and the size of the model Moon would increase.
• both the distance separating the model Earth and Moon and the size of the model Moon would decrease.
• the distance separating the model Earth and Moon would increase while the size of the model Moon would decrease.
• the distance separating the model Earth and Moon would decrease while the size of the model Moon would increase.

Original Version:

In your scale model of the Earth and the Moon, the Earth is represented by a baseball. If instead you represented the Earth by a basketball, then

• both the distance separating the model Earth and Moon and the size of the model Moon would increase.
• both the distance separating the model Earth and Moon and the size of the model Moon would decrease.
• the distance separating the model Earth and Moon would increase while the size of the model Moon would decrease.
• the distance separating the model Earth and Moon would decrease while the size of the model Moon would increase.

Editing Comments

I changed the wording a little bit. Instead of the Earth being represented by a bigger object, the baseball (that was once the Earth) becomes the scale model representation of the Moon. I think this way it requires a little more thought and is not as easy. — Aaron Lee 2009/09/04 02:24

Current Version

Suppose you take an optical spectrum of a thin, cool cloud of gas next to (but not directly along the line of sight to) a hot bright star. The spectrum may show

• a bright continuum and absorption lines.
• only absorption lines.
• a bright continuum and emission lines.
• only emission lines.

Original Version

Suppose you take an optical spectrum of a thin, cool cloud of gas next to (but not directly along the line of sight to) a hot bright star. The spectrum may show

• a bright continuum and absorption lines.
• only absorption lines.
• a bright continuum and emission lines.
• only emission lines.

Editing Comments

Explain the changes you made and why you made them. You MUST add your signature to the end of the comment. — Aaron Lee 2009/09/04 01:45

Current Version:

Suppose a student draws the energy levels of an atom with equal energy spacings (E = 1,2,3,…). You might deduce:

• The drawing is fine, as long as each energy level has a different energy.
• The drawing is incorrect; ionization would be impossible.
• The drawing is incorrect; the atom would essentially contain an infinite amount of energy.
• Nothing, we do not know enough to make any conclusion on its validity.

Original Version:

Suppose a student drew the electron energy levels of an atom with increasing energy spacings (E = 1, 3, 6, 12, …). You might deduce:

• The drawing is fine, as long as each energy level has a different energy.
• The drawing is incorrect; ionization would be impossible.
• The drawing is incorrect; the atom would essentially contain an infinite amount of energy.
• Nothing, we do not know enough to make any conclusion on its validity.

Editing Comments

Creator comment: This problem assumes that the students know there are an infinite number of energy levels in the atom. — Aaron Lee 2009/09/04 02:07

I changed the wording of the question to equal energy spacings. I think this will sound clearer. — Aaron Lee 2009/09/04 02:16

Current Version:

The Earth orbits the Sun at 30 km/sec. In 2006, NASA's New Horizons spacecraft was launched towards Pluto, traveling in a straight line at a constant speed of 16 km/sec. During one Earth-year, NASA will therefore receive radio messages from New Horizons that are

• all redshifted.
• all blueshifted.
• both redshifted and blueshifted.
• all redshifted, and the amount of redshift will increase from year to year.

Original Version:

The Earth orbits the Sun at 30 km/sec. In 2006, NASA's New Horizons spacecraft was launched towards Pluto, traveling at a speed of 16 km/sec. During one Earth-year, NASA will therefore receive radio messages from New Horizons that are

• all redshifted.
• all blueshifted.
• both redshifted and blueshifted.
• redshifted, and the amount of redshift will increase from year to year.

Editing Comments

I presume New Horizons travels more or less in a straight line (i.e. Pluto completes much less than 1 orbit in 1 Earth year). Assuming that's correct, I've edited the problem to try and make it clear that it's a question of detectors on the Earth (which is orbiting the Sun), and a message-emitting satellite that's traveling in a straight line and at a constant speed out into oblivion. — Chat Hull 2009/09/04 02:16

You're correct, it is 'essentially' a straight line, besides a gravitational assist from Jupiter and some minor tweaks here and there, I believe. Is “both blueshifted and redshifted” clear, in that sometimes its blueshifted, and sometimes its redshifted (compared to one signal being both)? — Aaron Lee 2009/09/08 10:11

Current Version:

Star Alex is observed and prominent absorption lines are detected in its spectrum. Its nearby companion, Star Aaron, is a similar star, but is rapidly rotating compared to Star Alex. The absorption lines of Star Aaron's spectrum are therefore

• all redshifted or all blueshifted relative to the absorption lines of Star Alex, depending on the direction Star Aaron is rotating relative to the observer.
• thicker than the absorption lines of Star Alex.
• exactly the same as the absorption lines of Star Alex.

Original Version:

Star Alex is observed and prominent absorption lines are detected in its spectrum. Its nearby companion, Star Aaron, is a similar star, but is rapidly rotating compared to Star Alex. The absorption lines of Star Aaron's spectrum are therefore

• all redshifted or all blueshifted relative to the absorption lines of Star Alex, depending on the direction Star Aaron is rotating relative to the observer.
• thicker than the absorption lines of Star Alex.
• exactly the same as the absorption lines of Star Alex.

Editing Comments

Current Version:

Two stars are observed, and one is twice as hot as the other. Both spectra contain a Hydrogen absorption line. However, the absorption line of the hotter star is

• located at half the wavelength of the cooler star's absorption line.
• located at twice the wavelength of the cooler star's absorption line.
• located at the same wavelength as the cooler star's absorption line.

Original Version:

Two stars are observed, and one is twice as hot as the other. Both spectra contain a Hydrogen absorption line. However, the absorption line of the hotter star is

• located at half the wavelength of the cooler star's absorption line.
• located at twice the wavelength of the cooler star's absorption line.
• located at the same wavelength as the cooler star's absorption line.

Editing Comments

If you do this question immediately after teaching Wien's Law, it will be too easy. I recommend saving this one for the beginning of the lecture AFTER Wien's Law is discussed. — Aaron Lee 2009/09/09 01:26

Original Version:

Which of the following is NOT a consequence of the present inflationary epoch?

• The rate of expansion of the universe is accelerating.
• The amount of observable mass in the universe is decreasing.
• The radius of the observable universe is decreasing.
• The ratio of mass density to the critical density is decreasing.

Editing Comments