Describing Experiments

Question 1

to get reliable results…

Answer 1

repeat experiment (at least 3 times) and calculate the mean

Question 2

to get valid results…

Answer 2

control the variables and make sure reliable results

Question 3

independent variable is the

Answer 3

variable you change

Question 4

dependant variable is the

Answer 4

variable you measure

Question 5

control variables are the

Answer 5

variables you keep the same

Question 6

hazards may include

Answer 6

microorganisms (pathogens)
chemicals (flammable or irritants)
fire
electricity

Question 7

making an experiment safer

Answer 7

identify hazard and reduce risk
e.g. for sulfuric acid, make sure wearing gloves and goggles
or uses heat proof mat with bunsen burner

Question 8

to get accurate results…

Answer 8

measure all of product accurately
e.g. for gases collect all gas in gas cylinder and measure volume
or parallax

Question 9

to get precise results…

Answer 9

use sensitive instruments with small increments (e.g. millimetre ruler)
use more decimal places

Question 10

when to use bar chart

Answer 10

if independent variable is categoric (blood types, metals…)

Question 11

to get full marks on graphs…

Answer 11

label axes with units 
neatly plot points with crosses 
make sure fill at least half space 
independent goes x axis 
dependant goes y axis

Question 12

planning an experiment ….

Answer 12

state what you're measuring
state what you're changing 
describe method and apparatus you'd use
describe what and how the control variables 
repeat for reliability