D2.Psy.1.9-12: The Scientific Methods at the Core of Psychology

Overview

Lesson Procedure

60-70 minutes of class time across 5 phases.

1. Warm-Up5-10 minutes
2. Direct Instruction20 minutes
3. Guided Practice15 minutes
4. Independent Practice15 minutes
5. Closure5-10 minutes

1. Warm-Up5-10 minutes

   Warm-Up Prompt

   "A friend says: 'I always remember things better when I study right before bed.' How could you find out whether this is true for most people, and not just for your friend? List three things you would have to decide before you could test it."

   Pairs share their lists. Students usually name what "remember better" means, who to test and what to compare bedtime study with. Write their decisions on the board under three headings that the lesson will name: What exactly is the claim? (hypothesis), How will we measure it? (operational definitions) and Compared with what? (control). Tell students that psychology is a science because it answers questions like this one with planned, measured and repeatable observations, not with how sure a person feels.

   Ground rule for the whole lesson: students design studies on paper only. They do not test classmates, family members or anyone else. Real research with people needs informed consent and an ethics review first (see D2.Psy.4.9-12).

2. Direct Instruction20 minutes

   Psychology is the scientific study of behavior and mental processes. What makes it a science is not its topic but its method: questions are answered with empirical evidence, meaning evidence gathered by systematic observation or measurement, and the procedure is described so that someone else can repeat it. Teach the toolkit below with the everyday examples in the table, then read Source 1, where Hermann Ebbinghaus explains in 1885 why he thought memory could be studied this way.

   The core tools of psychological science (everyday examples written for this page)

   Tool	What it means	Everyday example
   Hypothesis	A specific, testable prediction about how two or more variables are related	Students who take a practice quiz will recall more words two days later than students who reread
   Operational definition	A statement of exactly how a variable will be measured or produced	"Recall" = number of words written correctly from a list of 20 in 3 minutes
   Independent variable	The condition the researcher deliberately changes	Practice quiz or rereading
   Dependent variable	The outcome the researcher measures	Number of words recalled
   Controlled variable	A condition kept the same for everyone so it cannot explain the result	Same word list, same room, same study time
   Confounding variable	An uncontrolled difference between groups that offers another explanation	One group studies in the morning and the other at night
   Random assignment	Using chance to decide which participant gets which condition	Drawing names to form the two groups
   Sample and generalization	The people studied, and how far results can be applied beyond them	30 volunteers from one school may not represent all teens
   Replication	Repeating a study, ideally by other researchers, to see if the result holds	A second school runs the same procedure
   Theory	A broad, tested explanation that ties many findings together and produces new hypotheses	An explanation of why testing yourself strengthens memory

   Kinds of studies. An experiment changes an independent variable and measures a dependent variable while controlling other conditions, so it is the main design for testing cause and effect. A correlational study measures two variables as they already occur and asks whether they move together; it cannot by itself show which one causes the other, or whether a third variable drives both. Descriptive methods record behavior without testing a relationship: a case study examines one person or group in depth, naturalistic observation records behavior where it normally happens, and a survey asks many people questions about themselves.

   Self-report has limits. Introspection is a person's report of their own conscious experience. In Source 1, Ebbinghaus looks for a measure of memory that needs "less dependence upon introspection," one that does not rest on how a memory feels. Read Source 1 aloud. Paragraph numbers appear in the margin; "[...]" marks a cut.

   1We all know of what this method consists: an attempt is made to keep constant the mass of conditions which have proven themselves causally connected with a certain result; one of these conditions is isolated from the rest and varied in a way that can be numerically described; then the accompanying change on the side of the effect is ascertained by measurement or computation.

   2Two fundamental and insurmountable difficulties, seem, however, to oppose a transfer of this method to the investigation of the causal relations of mental events in general and of those of memory in particular. In the first place, how are we to keep even approximately constant the bewildering mass of causal conditions which, in so far as they are of mental nature, almost completely elude our control, and which, moreover, are subject to endless and incessant change? In the second place, by what possible means are we to measure numerically the mental processes which flit by so quickly and which on introspection are so hard to analyse? I shall first discuss the second difficulty in connection, of course, with memory, since that is our present concern.

   [...]

   3By somewhat less dependence upon introspection we can, however, by indirect means force these differences into the open. A poem is learned by heart and then not again repeated. We will suppose that after a half year it has been forgotten: no effort of recollection is able to call it back again into consciousness. At best only isolated fragments return. Suppose that the poem is again learned by heart. It then becomes evident that, although to all appearances totally forgotten, it still in a certain sense exists and in a way to be effective. The second learning requires noticeably less time or a noticeably smaller number of repetitions than the first. It also requires less time or repetitions than would now be necessary to learn a similar poem of the same length. In this difference in time and number of repetitions we have evidently obtained a certain measure for that inner energy which a half year after the first learning still dwells in that orderly complex of ideas which make up the poem. After a shorter time we should expect to find the difference greater; after a longer time we should expect to find it less. If the first committing to memory is a very careful and long continued one, the difference will be greater than if it is desultory and soon abandoned.

   • Reading a method description: Source 1, paragraph 1

     Match each part of the method Ebbinghaus describes to a modern term.

     Result: "keep constant the mass of conditions" = controlled variables; "one of these conditions is isolated from the rest and varied" = the independent variable; "the accompanying change on the side of the effect is ascertained by measurement" = the dependent variable. The sentence is a one-line definition of an experiment.

   • Finding a measure: Source 1, paragraph 3

     Ebbinghaus says a poem that seems totally forgotten may still leave a trace. How does he propose to measure something a person cannot recall?

     Result: Learn the poem again and count: "The second learning requires noticeably less time or a noticeably smaller number of repetitions than the first." The time or repetitions saved becomes a number that stands for what was retained, even when nothing can be recalled. This lesson calls it the savings measure.

   • From a claim to a hypothesis (the warm-up claim)

     Turn "I remember things better when I study right before bed" into a testable hypothesis with operational definitions.

     Result: Hypothesis: students who study a 20-word list in the last hour before sleep will recall more of the words the next morning than students who study the same list in the morning and are tested 12 hours later. IV: study time (before sleep or morning). DV: words written correctly in 3 minutes. Controls: same list, same study length, same 12-hour gap before the test.

   • Choosing a method

     Which design fits each question? (a) How often do drivers use a phone at one busy intersection? (b) Do people who report more exercise also report less stress? (c) Does a 10-minute walk before a test change scores?

     Result: (a) Naturalistic observation: record behavior where it happens. (b) Correlational study (often by survey): it measures two existing variables. (c) Experiment: randomly assign walk or no walk, then measure scores. Only (c) can test cause and effect.

   • Correlation is not causation

     An invented report: students who eat breakfast have higher quiz averages. Name two explanations other than "breakfast raises scores."

     Result: A third variable, such as more sleep or a calmer morning routine, could raise both breakfast eating and scores; or the direction could run the other way, since students who feel ready for school may be more likely to eat. An experiment with random assignment would be needed to test the causal claim.

   Close the segment by asking: Which of these tools did Ebbinghaus have to invent for himself, and which did he borrow from natural science? Students will test their answers against Sources 2 and 3 in the activities and quiz.

3. Guided Practice15 minutes

   Read Source 4 together. It is an invented study with invented data, written to show what a careful, ethical replication looks like. Work through the questions below as a class, then let pairs check the arithmetic.

   1Invented study summary, written for this page. A research team at a community college wanted to know whether a pattern Ebbinghaus reported for himself also shows up in a group of people. The team recruited 16 adult volunteers. Each volunteer read and signed a consent form that explained the task, said they could stop at any time without penalty, and promised that names would not be stored with scores. The college's research review board approved the plan before anyone was tested.

   2Each volunteer learned a list of 12 nonsense syllables until they could recite it twice without an error, and the team timed this first learning in seconds. A random draw then placed 8 volunteers in a group that relearned the same list after 1 hour and 8 in a group that relearned it after 1 day. For each volunteer the team computed savings: the first-learning time minus the relearning time, divided by the first-learning time, times 100, rounded to the nearest whole percent.

   3Savings scores (percent), 1-hour group: 53, 47, 58, 44, 61, 49, 55, 49. Savings scores (percent), 1-day group: 37, 41, 29, 38, 33, 45, 31, 34.

   4The team's conclusion: "Our volunteers saved more of their first effort after 1 hour than after 1 day, which fits the pattern Ebbinghaus described. The groups were small, and every volunteer was an adult at one college, so we cannot say how far the result holds for other people. Another team should repeat the study with a larger and more varied sample."

   1. Design. Name the independent variable (time before relearning: 1 hour or 1 day) and the dependent variable (savings, in percent). Point to the operational definition of savings in paragraph 2.
   2. Random assignment. Why did the team use "A random draw" (paragraph 2) instead of letting volunteers pick a group? Expected answer: people who choose a group may differ in ways that affect memory, such as how busy their day is. Chance makes the two groups alike on average, so a difference is more likely to come from the interval.
   3. Medians and spread. Order each group's scores. 1-hour group: 44, 47, 49, 49, 53, 55, 58, 61, so the median is (49 + 53) / 2 = 51 and the range is 61 - 44 = 17. 1-day group: 29, 31, 33, 34, 37, 38, 41, 45, so the median is (34 + 37) / 2 = 35.5 and the range is 45 - 29 = 16. Note the overlap: the highest 1-day score (45) is above the lowest 1-hour score (44), so the interval does not decide every individual's result.
   4. Ethics. Find the three protections in paragraph 1: informed consent, the right to stop without penalty, and names kept apart from scores, plus approval by a review board before testing.
   5. How far does it generalize? The sample is 16 adults at one college, a weak sample for claims about all people. The team says so itself in paragraph 4. A weak sample is not a wrong result; it is a limit on how widely the result can be applied.
4. Independent Practice15 minutes

   Students read Sources 2 and 3 on their own and use them, with Source 5, for the quiz and homework. Source 5 is an invented post, not a study: students should ask what it would take to test its claim, not decide whether gum helps memory. This page makes no claim either way.

   1Out of the simple consonants of the alphabet and our eleven vowels and diphthongs all possible syllables of a certain sort were constructed, a vowel sound being placed between two consonants.

   2These syllables, about 2,300 in number, were mixed together and then drawn out by chance and used to construct series of different lengths, several of which each time formed the material for a test.

   [...]

   3The aim of the tests carried on with these syllable series was, by means of repeated audible perusal of the separate series, to so impress them that immediately afterwards they could voluntarily just be reproduced. This aim was considered attained when, the initial syllable being given, a series could be recited at the first attempt, without hesitation, at a certain rate, and with the consciousness of being correct.

   [...]

   42. The reading and the recitation of the series took place at a constant rate, that of 150 strokes per minute. A clockwork metronome placed at some distance was at first used to regulate the rate; but very soon the ticking of a watch was substituted, that being much simpler and less disturbing to the attention. The mechanism of escapement of most watches swings 300 times per minute.

   [...]

   54. After the learning of each separate series a pause of 15 seconds was made, and used for the tabulation of results. Then the following series of the same test was immediately taken up.

   [...]

   67. Finally and chiefly, care was taken that the objective conditions of life during the period of the tests were so controlled as to eliminate too great changes or irregularities. Of course, since the tests extended over many months, this was possible only to a limited extent. But, even so, the attempt was made to conduct, under as similar conditions of life as possible, those tests the results of which were to be directly compared. In particular the activity immediately preceding the test was kept as constant in character as was possible. Since the mental as well as the physical condition of man is subject to an evident periodicity of 24 hours, it was taken for granted that like experimental conditions are obtainable only at like times of day. However, in order to carry out more than one test in a given day, different experiments were occasionally carried on together at different times of day. When too great changes in the outer and inner life occurred, the tests were discontinued for a length of time. Their resumption was preceded by some days of renewed training varying according to the length of the interruption.

   1The investigations in question fell in the year 1879-80 and comprised 163 double tests. Each double test consisted in learning eight series of 13 syllables each (with the exception of 38 double tests taken from 11-12 A.M. which contained only six series each) and then in relearning them after a definite time. The learning was continued until two errorless recitations of the series in question were possible. The relearning was carried to the same point; it occurred at one of the following times, — namely, after about one third of an hour, after 1 hour, after 9 hours, one day, two days, six days, or 31 days.

   [...]

   21. It will probably be claimed that the fact that forgetting would be very rapid at the beginning of the process and very slow at the end should have been foreseen. However, it would be just as reasonable to be surprised at this initial rapidity and later slowness as they come to light here under the definite conditions of our experiment for a certain individual, and for a series of 13 syllables. One hour after the end of the learning, the forgetting had already progressed so far that one half the amount of the original work had to be expended before the series could be reproduced again; after 8 hours the work to be made up amounted to two thirds of the first effort. Gradually, however, the process became slower so that even for rather long periods the additional loss could be ascertained only with difficulty. After 24 hours about one third was always remembered; after 6 days about one fourth, and after a whole month fully one fifth of the first work persisted in effect. The decrease of this after-effect in the latter intervals of time is evidently so slow that it is easy to predict that a complete vanishing of the effect of the first memorisation of these series would, if they had been left to themselves, have occurred only after an indefinitely long period of time.

   [...]

   3At any rate, even though only for my own case, I can to a certain extent give support to two of the values mentioned by tests which were made at other periods.

   1Invented social media post, written for this page. "Study hack that actually works!! Last week I chewed mint gum the whole time I studied for my chemistry test and got a 94, my best grade all year. My friend tried it too and said she felt way more focused. Everybody knows smell is tied to memory, so the gum must have locked the facts in. Try it before your next test!"

   2Under the post, 212 people clicked "like" and 15 people commented that the trick worked for them too.

   Task: in a short paragraph, explain what Source 5 would need before it counted as scientific evidence. Use at least three terms from the toolkit table, and say why 212 likes and 15 agreeing comments do not settle the question.

5. Closure5-10 minutes

   Exit ticket: "Name one thing Ebbinghaus did that makes his work scientific and one limit a modern psychologist would point out. Quote the source for each."

   Teacher notes. (1) Ebbinghaus is a historical source chosen to show how the method began; this page does not present his 1885 numbers as current memory science, and his own words say how narrow they are. (2) Today research with human participants needs informed consent and an ethics review, which D2.Psy.4.9-12 covers. (3) Sources 4 and 5 are invented for teaching; their data and comments are not real. (4) If a student asks to run a memory test on classmates, keep it as a paper plan; a teacher-led class demonstration with anonymous, voluntary participation should follow your school's rules.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   Source 2, paragraph 6 says that when "too great changes in the outer and inner life occurred, the tests were discontinued for a length of time." What did stopping the tests protect?

   AThe comparison, by keeping large uncontrolled changes out of the results BHis health, by giving him a rest he had earned after many months of work CThe forgetting data, since long breaks were themselves one of the intervals DThe material, by giving him time to write new and harder syllable series

2. Question 2 of 20 · Multiple Choice

   According to Source 1, paragraph 2, what two difficulties seem to stand in the way of studying memory with the method of natural science?

   APaying volunteers fairly, and then finding a scientific journal that will publish the results BHolding shifting mental conditions constant, and putting quick mental events into numbers CChoosing poems over numbers, and deciding which language the material should use DGetting approval from a review board, and keeping participants' names private

3. Question 3 of 20 · Multiple Choice

   Which sentence from Source 1, paragraph 3 states a prediction that an experiment could test?

   A"A poem is learned by heart and then not again repeated." B"We will suppose that after a half year it has been forgotten" C"After a shorter time we should expect to find the difference greater" D"It then becomes evident that, although to all appearances totally forgotten, it still in a certain sense exists"

4. Question 4 of 20 · Multiple Choice

   Source 2, paragraph 2 says the syllables "were mixed together and then drawn out by chance" to build each series. What does drawing by chance protect against?

   AIt makes every series easy enough to learn in a few repetitions BIt lets Ebbinghaus skip counting how many repetitions each series took CIt turns the syllables into meaningful words that are easier to recall DIt keeps the researcher from making some lists easier

5. Question 5 of 20 · Multiple Choice

   In Source 2, paragraph 4, reading and recitation always happen "at a constant rate, that of 150 strokes per minute." In modern terms, the rate is

   Aa controlled variable Bthe dependent variable Cthe independent variable Da confounding variable

6. Question 6 of 20 · Multiple Choice

   Why does Ebbinghaus conclude in Source 2, paragraph 6 that "like experimental conditions are obtainable only at like times of day"?

   AWatches ran at a different speed in the morning than in the evening BA person's mental and physical condition follows a 24-hour cycle CHe found that the syllables were easier to read in daylight than by lamplight DThe tests had to fit around a teaching schedule that changed every day

7. Question 7 of 20 · Multiple Choice

   In the investigations described in Source 3, paragraph 1, which variable did Ebbinghaus change on purpose from one double test to another?

   AThe number of syllables in each series BThe time of day at which he read the series CThe delay before relearning DThe number of errorless recitations required

8. Question 8 of 20 · Multiple Choice

   Ebbinghaus writes in Source 3, paragraph 3 that his support comes "only for my own case." Which limit of his research does this phrase point to?

   AHis results come from one person and may not generalize BHis results were never written down or published anywhere CHe measured memory with feelings rather than with numbers DHe did not hold any conditions constant from one test to another

9. Question 9 of 20 · Multiple Choice

   Which statement is an operational definition of "learned" of the kind Ebbinghaus uses in Source 2, paragraph 3?

   ALearned means the person feels the list has become familiar and easy BLearned means the list was studied for a long time and with some care CLearned means a first-try recitation, without hesitation, at a set rate DLearned means the person has understood the meaning of every item on the list

10. Question 10 of 20 · Multiple Choice

    In Source 4, paragraph 2, the team computes savings from timed learning instead of asking volunteers how well they think they remember. Why is the timed measure stronger?

    AIt guarantees that the 1-hour group will have the higher scores BIt removes the need for a consent form or a review board CIt lets each volunteer choose the group that suits their schedule DIt counts behavior the same way for every person

11. Question 11 of 20 · Multiple Choice

    Using the invented data in Source 4, paragraph 3, what is the mean savings score of the 1-day group?

    A35.5 B34 C36 D16

12. Question 12 of 20 · Multiple Choice

    Which claim goes beyond what the invented study in Source 4 can support?

    AWaiting a day before relearning causes every person to lose about a third of what they learned BThese 16 volunteers saved a larger share of their first effort, on average, after 1 hour than after 1 day CThe two groups' scores overlap, so a few 1-day volunteers saved more than a few 1-hour volunteers DRandom assignment makes it more likely that the interval, not group makeup, explains the difference

13. Question 13 of 20 · Multiple Choice

    An invented study surveys 300 students and finds that those who report more hours of sleep tend to have higher grades. What can the researchers conclude from this design alone?

    ASleeping more causes higher grades for most students in the sample BSleep and grades are related, but the cause is not yet known CHigher grades cause students to sleep more hours each night DSleep and grades are unrelated, because nothing was manipulated

14. Question 14 of 20 · Multiple Choice

    Source 4, paragraph 4 asks another team to repeat the study with a larger and more varied sample. What is this step called, and why does it matter?

    APeer review: editors decide whether a journal should print the study BRandom assignment: chance decides which group each person joins COperational definition: the team states exactly how it measured savings DReplication: it tests whether a result holds beyond one sample

15. Question 15 of 20 · Short Answer

    Source 2, paragraph 6 describes two more safeguards: keeping "the activity immediately preceding the test" steady, and the "renewed training" before tests resumed after a break. For each safeguard, explain what problem it prevents and name the kind of variable it deals with.

    Show model answer

16. Question 16 of 20 · Short Answer

    A coach says (an invented claim): "Players who picture their free throws before practice make more of them." Rewrite the claim as a testable hypothesis. Give the independent variable, the dependent variable with an operational definition, and one controlled variable.

    Show model answer

17. Question 17 of 20 · Short Answer

    Apart from who was tested, Source 3, paragraph 2 names conditions that limit how far the forgetting pattern can be generalized. Quote them, explain why each one matters, and describe one change to the method that would test whether the pattern holds more widely.

    Show model answer

18. Question 18 of 20 · Short Answer

    Use the invented data in Source 4, paragraph 3. Compute the mean savings score of the 1-hour group. Compare it with that group's median from Guided Practice, say what the comparison suggests about how the scores are spread, and give one reason to be cautious about generalizing.

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19. Question 19 of 20 · Short Answer

    Name the best research design for each invented question and justify your choice for (c): (a) How do strangers greet each other in a train station? (b) Do teens who spend more time outdoors report better moods? (c) Does practicing a speech in front of a mirror change how many filler words ("um," "like") a speaker uses?

    Show model answer

20. Question 20 of 20 · Short Answer

    Explain how a theory differs from a hypothesis and from a single finding. Use the forgetting pattern in Source 3, paragraph 2 as the finding in your answer.

    Show model answer

These standards connect to D2.Psy.1.9-12: prerequisites to review first, parallel standards at the same level, and next steps that build on it.

Standard text: National Council for the Social Studies (NCSS), The College, Career, and Civic Life (C3) Framework for Social Studies State Standards: Guidance for Enhancing the Rigor of K-12 Civics, Economics, Geography, and History (Silver Spring, MD: NCSS, 2013). NCSS was not involved in the production of this lesson and does not endorse it.