Spotting Control Variables. To be able to identify control variables and state why they are important. Leveled Assessment

Levels Level 4 – identifies one thing to change Level 5 – recognition of factors which may affect the experiment, Level 6 – explanation of how different variables could affect the experiment.

Indigestion You are going to carry out an experiment to identify which indigestion tablet is most effective Why do you get indigestion?

Acid and Alkali You get indigestion if you have two much stomach acid. You can treat this by having an alkali indigestion tablet. But which one should you take? You need to plan and implement an ACCURATE investigation

Planning You have: 3 indigestion tables, hydrochloric acid Beakers, water, mortars to crush the tablets. Water, Measuring cylinders methyl orange indicator (goes red when acid – orange when neutral/alkali) Take 5 min and see what ideas you can come up with and we can share ideas.

Experiment Grind an indigestion tablet up using a pestle a mortar Place this into a test tube, adding 10cm3 of water Now add 4 drops of methyl-orange to the test tube Add 1cm3 of acid to the test tube using a dropping pipette, and record how much you needed to add before the methyl-orange changed from orange to red (make sure you stir the solution thoroughly) Repeat this experiment using the other two indigestion tablets

State your variables What variables do we have? This is the assessed part – so over to you! Look at the method on the board and identify the variables and fill out the table!

Table of Results  

Conclusions Which one is best? How can you tell?

Levels Level 4 – identifies one thing to change Level 5 – recognition of factors which may affect the experiment, Level 6 – explanation of how different variables could affect the experiment,