Scaffolding the Factor Label Method in the Chemistry Classroom


There is one particular part of chemistry class that trips up students a lot, and it’s using the factor label method.  Students need the factor label method for all sorts of conversion and stoichiometry problems throughout the entire year of chemistry.  The problem is that the factor label method itself is a combination of other skills, any of which a student might struggle with.


Here is a list of the skills students need to be able to do the factor label method and how I address them:


  1.  Reading the question! So many students, including ELL and non-ELL students, struggle with decoding a word problem and figuring out what the question is even asking.  And when chemistry vocabulary is involved, even more so.


How to address this reading need:


With struggling students, I create practice questions where all they do is tell me what key information is given in the problem and what they need to solve for in the problem solving process.  That way, I can identify and help students who need help reading the question and determining what the question is actually asking, because if they can’t read the problem, they certainly can’t do the problem.

[convertkit form=5060181]


2.   Practice path-finding!  Once students know what they are given and what the question is asking, students struggle with figuring out exactly how to get from “point A” to “point B”.  It takes a bit of practice to know that to calculate the length of time to build something in minutes when given years, that you have to convert years to days and then days to hours and then hours to minutes.  This “path-finding” problem compounds itself when students are learning a new concept in chemistry and they need to learn how to go from the mass of a reactant to the moles of that reactant to the moles of a product and then the mass (or volume or percent yield…) of the product.


How to address this pathfinding need:

With students who struggle with “path-finding”, I use practice questions that only ask them to figure out the path, not even do the calculations.  They practice looking up conversion factors and practice thinking through the chemistry, without worrying about pushing the right buttons on the calculator and getting it all wrong in the end.  By having students practice doing this, it also helps them practice WRITING DOWN ALL THEIR STEPS.  So often, students who struggle have a harder time than they would if they only wrote down their work.


3.  Practice the calculations!  Once they know what’s given and what they need to find and they have the path planned out, then the actual math or calculations can trip them up.  I have students who can write it all down but have a tough time pressing the right buttons on their calculator or <GASP> can’t do it by hand.  Arithmetic skills are at an all-time low (as you all know already) and when you’re a chemistry teacher, you’re a math teacher too!  I review the orders of operation in my chemistry class.


How to address this calculating need:

To help students to practice performing calculations, I do exercises in class where I set the whole problem up for them and then I have them set up the math and complete it.  Usually after a few practice rounds of this, I can identify students who are struggling with the math and get them extra support.


And here’s another quick tip for teaching the factor label method:

When I was taught the factor label method back in as a high school sophomore in Mrs. Sears’ honors chemistry, I was taught to write the conversion factors in “monkey bars”, which is what she called them!  Instead of parenthesis/fractions, she had us write them like this:


You know, I still use them in my own problem solving and in my classroom.  There is just something a little simpler about writing a grid instead of writing ( ) ( ) ( ) ( ).  Fewer lines to mess up and I think it really helps students (like me!) with pretty terrible handwriting.


If you would like to check out my factor label method pages, you can find them here.

They are included in my Differentiated Chemistry Homework for the Whole Year Bundle here.

science and math with mrs lau

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