ICAS Science flashcards
ICAS Science · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Qualitative observation
- An observation recorded as a description rather than a number, such as the colour, texture or smell of a substance; it cannot be averaged.
- Quantitative observation
- An observation recorded as a number with a unit, such as 12.4 g or 25 mL, so that results can be compared, graphed and averaged.
- Parallax error
- An error caused by viewing a scale from an angle, so the reading appears shifted; avoided by placing the eye level with the mark being read.
- Meniscus
- The curved surface of a liquid in a container; for water in glass the curve dips, so volume is read at the lowest point at eye level.
- Instrument precision
- The smallest scale division an instrument can show; a ruler marked in millimetres has a precision of 1 mm and readings are uncertain by about 0.5 mm.
- Accuracy and precision
- Accuracy is how close a reading is to the true value; precision is how close repeated readings are to each other. A set can be precise but inaccurate.
- Random error
- Unpredictable variation in readings caused by the observer, instrument or conditions; reduced by taking several measurements and using their mean.
- Independent variable
- The variable the investigator deliberately changes in an experiment; it is plotted on the horizontal x-axis of a graph.
- Dependent variable
- The variable that is measured in response to a change in the independent variable; it is plotted on the vertical y-axis of a graph.
- Line of best fit
- A straight or smooth line drawn through the middle of plotted points to show the overall trend; it need not pass through every point.
- Interpolation
- Estimating a value that lies between two known data points on a graph or table; usually reliable because it stays within the measured range.
- Anomalous data point
- A reading that clearly does not follow the trend of the other data; it is usually rechecked and excluded from trend analysis.
- Correlation versus causation
- Two variables changing together is correlation; this does not prove one causes the other, because a third factor may affect both.
- Hypothesis
- A testable statement predicting the relationship between two variables, worded so that collected evidence could support or refute it.
- Prediction
- An expected result for a particular situation, worked out from a pattern, rule or hypothesis before the measurements are made.
- Conclusion
- A judgement about whether the results support the hypothesis, based only on the evidence collected during the investigation.
- Extrapolation
- Predicting values beyond the range of data actually measured; it is less reliable than interpolation because the trend may change.
- Control group
- The group in an experiment that does not receive the independent variable; it provides a baseline for judging the size of any effect.
- Fair test
- An investigation in which only the independent variable is changed and every other relevant condition is kept constant.
- Controlled variable
- A factor kept the same in every trial so that it cannot explain any differences seen in the dependent variable.
- Reliability
- How consistent repeated measurements are; it is improved by repeating trials, using the same method and averaging the results.
- Validity
- Whether an investigation actually measures the variable it claims to measure and genuinely tests the stated hypothesis.
- Random sampling
- Selecting individuals from a population in a way that gives each an equal chance of selection, so the sample is not biased.
- Placebo
- An inactive or fake treatment given to a control group so that expectations and suggestion do not confound the results.
- Measuring cylinder
- A tall vessel with a volume scale used to measure liquid volume; choose one that will be more than half full and read at eye level.
- Risk assessment
- A check made before an experiment that lists the hazards, how likely and serious each is, and the controls used to reduce risk.
- Density
- The mass of a substance per unit volume, calculated as density = mass divided by volume; units are grams per cubic centimetre or kilograms per cubic metre.
- Average speed
- The total distance travelled divided by the total time taken; speed = distance divided by time, with units such as metres per second.
- Percentage change
- The size of a change expressed relative to the original value, calculated as (new value minus old value) divided by old value, times 100.
- Order of magnitude
- A rough power-of-ten estimate of a quantity, used to check quickly whether a calculated answer is sensible.
- Surface area to volume ratio
- As an object increases in size, its volume grows faster than its surface area, so the ratio of surface area to volume falls.
- Scale factor
- If every length of a shape is multiplied by a factor k, then areas are multiplied by k squared and volumes by k cubed.