Experimental skills
- Planning
- independent and dependent variables
- keep variables constant
- control experiment
- five values, three repeats
- Results tables
- time / s
- no units in body
- same decimal places
- percentage change
- Graphs and charts
- independent variable on x-axis
- more than half the grid
- × or ⊙, best-fit line
- histogram bars touch
- Biological drawings
- sharp pencil, no shading
- ruled label lines touching
- image size ÷ actual size
- measure in mm
- Evaluating
- anomalous results
- repeats and mean
- sources of error
- specific improvements
- Indicators and tests
- limewater: milky
- hydrogencarbonate: yellow, red, purple
- universal indicator: pH
- litmus: red acid, blue alkali
- Errors and uncertainty
- zero errors
- random and systematic errors
- equal within ±10%
- accuracy and precision