How Science Works The following PowerPoint is aimed at enhancing skills learnt at GCSE when performing experiments. Pupils must commit the terminology to memory to allow more complex scrutiny of the data obtained.

Terminology Work through each of the following key words and recite their meanings Hypothesis A prediction based on existing scientific knowledge/understanding. Independent Variable The variable which is chosen for an experiment to be manually changed. Dependant Variable The variable being effected as a result of dependant variable being changed. Random Error Errors caused by lack of care during measurements, data contains poor accuracy to be considered as good evidence. Systematic Error poor technique, a badly calibrated instrument produce measurements with systematic errors. The data may be precise but does not have enough accuracy to give good evidence.

Terminology Work through each of the following key words and recite their meanings Accuracy Accuracy tells you how close your measurements of the variable are to the true value of the variable. Precision Precision tells you how precisely you can make your measurements. Precision is shown by the number of decimal places given for a measurement. It can be expressed as a percentage of 100% minus the maximum error. Uncertainty There is no such thing as perfect measurement. Statements are made with a certain degree of uncertainty. As a rule of thumb, experiments try to reduce uncertainty to a minimum.

Terminology Work through each of the following key words and recite their meanings Continuous variable Is one that we measure and any numerical value is possible. Eg the volume of gas given off was 34.5cm 3. Discrete variable Is one that can only have certain numerical values. Eg Number of marble chips used in an experiment. Catagoric variable Is one that is best described by a label (a word). Eg the has given off was CO 2. Ordered variable Is one where you can put the data in order but not give an actual amount. Eg Small, medium and large marble chips used. Control variable Is one that we keep constant so it does not affect the results.

A Gentle Introduction to How Science works. How Did You Do? Jot down what links where

Other Terminology Reliable A consistent value is obtained after many repeat measurements. Valid The measurements taken can be used to give the required data. Range The difference between the lowest and highest reading. Mean Calculated by adding the total of all the readings and dividing by the number taken. Linearity The reading is directly proportional to the magnitude of the variable that causes the reading to change.

Evaluating Results A conclusion must be able to be taken from the results obtained. This may involve a final calculation of a quantity or simply a statement of a relationship established between two variables when all others have been controlled. Any comment must be evaluated in terms of Reliability of data (can improvements reduce uncertainty) Discuss method/procedure appropriateness to reduce errors Consider calculated uncertainties to evaluate accuracy in findings Possible suggestions for improvements to increase validity of data A final statement to indicate direction i.e. what further steps could be taken to strengthen conclusions made.