Year 9 Science · Unit 1 · Lesson 18
Foundation Worksheet
Learning Goals
Match each term to its definition
Draw a line connecting each study type on the left to its correct description on the right. Or write the matching letter next to each term.
| Study type | Your answer | Description |
|---|---|---|
| Descriptive study | A. Researchers randomly assign participants to a treatment or control group to test whether an intervention works. | |
| Cohort study | B. Researchers compare people who have a disease (cases) with similar people who do not (controls) to find differences in exposure. | |
| Case-control study | C. Researchers follow a group of people over time and record who develops a disease and what exposures they had. | |
| Randomised controlled trial (RCT) | D. Researchers test a treatment by giving one group the real treatment and another group a placebo, without participants knowing which they received. | |
| Double-blind trial | E. Researchers document who is getting sick, where, and when, without yet explaining why. |
Fill the gap
Choose the correct word from the word bank to complete each sentence.
The study of disease patterns in populations is called . In 1854, Dr John Snow used this approach to trace a cholera outbreak to a contaminated water pump, without needing to know the microscopic cause. Before conducting research on human participants, scientists must obtain the voluntary agreement of participants who understand the study's risks and benefits. A variable is a hidden third factor that can create the false appearance of a link between two things. For example, the number of ice cream sales and drowning rates both rise in summer, but ice cream does not cause drowning, hot weather is the variable. When two things are linked statistically, this is called a . However, to establish that one thing actually causes another, scientists need controlled experiments and multiple lines of evidence. A is an inactive treatment given to a control group so that any psychological effect of "receiving treatment" does not distort the results.
1. Explain why a randomised controlled trial (RCT) is considered the "gold standard" for testing whether a treatment works. What makes it better than a cohort study?
2. The Tuskegee syphilis study withheld treatment from participants without their knowledge. Identify the key ethical principle this study violated and explain why this principle is essential in disease research.
Wrap Up
In one sentence, what is the main idea of this lesson?