As I teach and tutor A level Chemistry I notice that some of my students find the maths used in solving computation type problems easy to follow and others seem to find these types of problems the area where they lose the most points on their end of topic exams. They understand the concept being assessed in the question but get caught up in the maths – they forget to carry the minus sign, multiply by a coefficient or the units don’t cancel out. And before they know it, the question doesn’t make any sense anymore and they look at their paper with frustration!
Does one of these scenarios sound like you? Do you wish there was an easier way to solve these types of problems and achieve a good grade in A-level Chemistry?
POGIL – Sounds Weird But Makes Sense
POGIL is an acronym for Process Oriented Guided Instructional Learning. The process was formulated in the late 1990s as a way to teach General Chemistry in the United States. It sounds weird but once you see it in action it makes perfect sense! I find that once I teach the concept to my students, it helps the students who like maths and don’t like maths get the correct answer to computational type problems all of the time. All you have to do is complete the following steps:
- Read the question carefully and underline any keywords or units.
- Circle the initial conditions.
- Circle the final conditions.
- Ask yourself “what steps do I need to complete in order to get from the initial conditions to the final conditions?”
- Write down any unit conversions that you may need to convert from one unit to the next.
- Make sure that the units cancel out as you move from one step to the next.
Example of POGIL In Action
Here’s a sample problem you can solve using POGIL. It’s a type of problem that may be seen on the module on amount of substance on Paper 1.
Q. How many chloride ions are present in 5.6 g of aluminium chloride?
Use POGIL to map out a path from the initial conditions to the final conditions.
- Initial condition: 5.6 g of aluminium chloride.
- Final condition: amount of chloride ions.
Write down the steps you need to take in order to get from the initial to the final conditions:
- Compute the molar mass of AlCl3 which is 133 grams mol -1.
- Convert grams of aluminium chloride to moles of aluminium chloride.
- Recall that there are three moles of chloride ions per mole of aluminium chloride.
- Convert moles of aluminium chloride to moles of chloride ions.
- Recall that there is Avogadro’s number of chloride ions per mole of chloride ions.
- Convert moles of chloride units to units of chloride ions.
Graphically the process looks like this:
By following the steps involved in POGIL when solving computational type problems my students get the correct answer the first time!
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