When should we first teach variables in school math? And how?

Question

From a pedagogical point of view, when is the "right" moment to introduce letters and variables to school children?

Let's say we taught arithmetic, the four operations, did computation exercises, or even "disguised" equations, when in place of a variable we use a box, and ask what numbers should we put in that box.

How should we introduce the practice of using letters, to make the transition from arithmetic to algebra?

The context: I'm a high school teacher, I do my job pretty well and have good results with my high school students, but recently I've been tutoring a fifth grader, and for the future it is possible that I would have to teach also in middle school (grades 5-8). I find it is kind of hard to work with this student I tutor; he is having a hard time doing/understanding even simple stuff (simple for me, of course), and I find that variables/letters "intimidate" him.

How should I introduce and motivate using letters?

I feel that even high schoolers are sometimes "intimidated" by letters. I once had a student that said, "teacher, I really loved mathematics in the past, but only when we worked with numbers. Since we were introduced to letters in math, I don't like it anymore."

What should we do to avoid this issue? i.e., How should we introduce letters/variables in order for children to understand them better and not hate algebra?

Answer 1

You don't need 1-letter variable names to do algebra. Basically, as soon as you start giving story problems to children, you need to start teaching algebra techniques. You can teach them as "easier ways" to solve the problems, that help kids "keep track of things" and "avoid mistakes".

Most computer programming languages (including spreadsheets with named cells) allow using long variable names. Languages like Logo have been successfully taught to primary school children.

The key is to clearly distinguish the long variable names from other text that might represent operations. Parentheses can suffice.

After not very long, children will get tired of writing out complete variable names. At this point, you can show them how to:

• Draw a picture if it helps to understand the variables.
• Explicitly abbreviate their variable names.
• At the end of the problem, write a short summary of the answer, and circle it in a cloud. For example:

At the beginning of the problem:
(# apples) = (number of apples)
…
At the end of the problem:
There are 7 apples.

And later on:

At the beginning of the problem:
(a) = (number of apples)
…
At the end of the problem:
There are 7 apples.

And later on:

At the beginning of the problem:
a = number of apples
…
At the end of the problem:
There are 7 apples.

Answer 2

I'm not an expert, but I understand the curriculum in Russia has gone back and forth on this point, with a lot of debate.

Generally, grades 1 to 4 are spent on the basic arithmetic operations, while grades 5 and 6 are mainly focused on: familiarizing students with the algebraic properties of numbers in a concrete way, systematizing and extending knowledge of fractions and decimal numbers, and studying signed numbers. Algebra starts in earnest in grade 7.

In the earlier grades, letters are used freely to state the general properties of numbers, to state formulas, and to write down simple equations. But they are not used systematically to manipulate expressions and equations and isolate an unknown as is done in algebra. In the 1970s, there was an effort to introduce algebra in grades 5 and 6 (called grades 4 and 5 at that time, since school then started at age 7). But it was found that by turning the process of solving arithmetic problems into a kind of algorithm, it took away a lot of the opportunity for kids to experiment and develop intuition for numbers. So there was a kind of "back to basics" reaction in the 1980s on this point.

Let me give an example to show what I'm talking about. Your sister had twice as many books as you do until a friend gave her 6 books today, and now she has 24 books. How many books do you have? Before she was given the six books, she had 24 - 6 = 18 books. So you have 18/2 = 9 books.

If you compare this solution with the mathematically equivalent steps in solving $2x + 6 = 24$, the difference is that the steps have a concrete meaning in the first solution, but possibly not in the second. So the first solution helps develop intuition for numbers in a way that the second may not. In fact, the second kind of solution is more likely to make sense to you if you are already proficient in the first kind and can therefore make the connection between the two. There needs to be a phase in which kids are encouraged to think concretely about problems rather than turning them into equations and going on auto-pilot.

However, there is a role for equations where they clarify the meaning of an operation. For example, it's useful to say that subtracting $7$ from $12$ means finding the number $x$ for which $7 + x = 12$. Or that dividing $\frac{4}{7}$ by $\frac{3}{5}$ means finding the number $x$ for which $\frac{3}{5} \times x = \frac{4}{7}$. Using formulas like $d = vt$ or $A = \frac{1}{2}bh$ also accustoms students to the use of variables without turning everything into algebra.

Answer 3

The letters intimidate him because he doesn't recognise them or their meaning. Only introduce them when he demonstrates that he is ready.

Ask him what his initials are. When he tells you, ask him if he would recognise he was being addressed if you used only his initials. When he (hopefully) says yes, then ask him if distance might have an 'initial' he could suggest so that when you used that letter, he would know you were referring to distance. Hopefully he will suggest 'd'. And so on.

You could even introduce the lesson by having every student only address other students using their initials... good fun, but it breaks down the resistance to the dreaded 'letters' :)

Then only introduce variables which have immediately obvious 'initials', such as p for price or pizza, h for height, l for length, a for adults, h for hours, etc, depending on the context.

Only after he has begun to associate letters with practical measurements and quantities should you mention that 'algebra is just the same... it just uses abbreviations to simplify things, just like his initials.

Any talk of x and y and z will re-introduce the fear of symbols. It's better to wait until he gets frustrated with 'all these words' and the idea of an abbreviation is his idea...

I often tell students that they have been using algebra 'for ages', only they didn't realise it. Then I tell them a word story like this: Jimmy goes to the bank and gets out enough money for three pizzas. On his way to the pizza shop, he finds 8 dollars on the footpath (sidewalk). When he gets to the shop he has 41 dollars. How much was each pizza going to cost him?

Almost all students who can add and subtract will get it correct very quickly.

Then say "I'm going to write the algebra abbreviation for that story, and write 3p + 8 = 41 on the board.

Say "if he hadn't found the 8 dollars, would he have more or less?' They all will say 'less'.

Then write 3p = 41 - 8

NB! don't introduce any rules about sides and signs and what you do to one side, etc, same for words like solve and expression and equation. These should only come after the process is understood using things they already know... or you'll turn him off all over again.

and ask how much money did he get from the bank? They will say '33'

3p = 33

The say 'So, how much was each pizza going to cost? They will say '11 dollars'. Trust them to refer to what they already do at the shops, not what you have to tell them about dividing, or whatever. Trust that their experience already contains algebraic processes, only they didn't call it that... but they were perfectly good at getting it right. Hint! money and food questions are very familiar to almost every student everywhere.

Then say 'That's all algebra is: an abbreviation for words, using a consistent set of rules.' They will get it... and then wait for them to ask about or discover or intuit or teach each other the rules. Teaching is as much about asking and listening and enabling as it is about telling.

Then make up similar stories that you read out and they write the abbreviations for. Include things like 'on the way he lost 12 dollars', etc.

I have done this for 25+ years and it it has 'worked' almost every time with almost every student, so long as they can add, subtract, multiply and divide competently. If not, then address that first.

Only introduce abstract concepts and 'letters' when students are more than comfortable... and you have exhausted most of the other letters and they are ready for some meat in the sandwich.

Hope this helps

Answer 4

Sorry for adding another answer, I'm new here. This paper:

Carraher, D. W., Schliemann, A. D., Brizuela, B. M., & Earnest, D. (2006). Arithmetic and algebra in early mathematics education. Journal for Research in Mathematics education, 87-115.

is a good start. Lots of references to existing research. I can add a link but not sure if it's behind a paywall.

A quick glance tells me that the gist is that you can introduce variables as early as 9-10 years of age but that it's important to build algebraic thinking by looking for patterns in number properties first.

EDIT: Adding some detail as per Ben's comment.

This is something of a rabbit hole. It seems that very young children can solve equations with boxes, question marks, or even letters to represent unknowns, however, they may not be truly engaging with variables in and algebraic way. The question becomes whether they are actually operating on unknown values or using "pure-arithmetic" strategies like counting and working backwards. The authors present several sources claiming to show that young children (at least as young as third grade) can work with symbols for unknowns in an algebraic way, and that algebra and arithmetic are not entirely separate modes of thinking.

For anyone wanting answers to the posted question, I'd suggest reading the brief literature review in the above article. The article itself is really focused on using functional relationships to teach arithmetic, rather than variables in particular. The authors seem to feel that there is strong evidence that students can engage with variables in a meaningful way from about age 8 or 9, but that we need to be careful about what we define as "meaningful," since researchers who argue that younger children aren't "developmentally ready" may have somewhat rigid views about meaningful use of variables and the nature of the relationship between arithmetic and algebra.

Answer 5

I'm a teacher at a small Christian school and so I fill a lot of gaps. I've taught 4th, 5th, 6th, 7th, Alg. 1, and Geometry, as well as tutoring everything in between up to Pre-Calc with great success.

My 4th graders just recently got introduced to algebra. I've found that at that age, a lesson dedicated to the subject matter is more than sufficient for mastery of the simple idea that a letter represents some unknown or variable amount.

Our curriculum is very good at building from the "boxes" mentioned in other's posts, and lends opportunity for a teacher to get students excited earlier in the year if the class seems ready, by telling them, "What you're really doing is Algebra! The only difference, is that in Algebra, a letter is used instead of a box!" This takes the intimidation factor out of algebra, makes the students feel smart, and excited about furthering their math knowledge. They beg for the lesson on algebra before you get there, and then as a teacher, you have an easy time keeping their attention and making sure correct steps are used in finding the correct answer that will build a foundation in 4th grade that they'll use all the way through Algebra.

I've also found while teaching higher grades, that students without this foundation have a much harder time of developing it after they've developed instead, an aversion to algebra in general, but a similar approach can definitely be done in a tutoring scenario.

Answer 6

Many elementary students have a problems with the equals sign. They may not be able to solve for the missing number 3+2=__+1. They see = and think "the answer is". Therefore they will fill in the blank with 5, which is of course incorrect. If you add to the difficulty of this problem with a variable 3+2=x+1, many students and teachers will think the problem is that there is an x and not realize the student just doesn't understand how equality works.

BTW this is why students often in a multi-step problem may write: 3+2=5-2=3+17 =20.

I suggest that you introduce variables first where they are the answer to the problem, so that you have 3(77) = x and 3(42-4.1)=x etc. If the student is overwhelmed by a letter, replace with a box and then show that they are the same.

Once the student is comfortable with x as the missing answer, go on to problems where one side of the equality is a single number and the other side is an expression containing a variable. Start with simple problems that the students can do mentally and then proceed to more complex examples. For example 3+x=5 and x- 7 =2. Proceed to more complex problems such as 3x+2 =8.

Finally make sure the students understands how equality works, by giving problems such as 3+11 = __*7. If the student understands that, then you can proceed to replacing these examples with variables.

Above all be patient.

Answer 7

I would start early with "boxes" -- just empty squares and playing "what goes in the box?" for simple equations. Works well for kids as young as second grade and definitely by 4th. It makes it much easier to introduce letters as variables later, with the understanding that they act like containers. And, as someone else said, you can bridge the gap by modeling story problems with known quantities (at least that's what my son gets in 4th grade).

I should note, I've used boxes for adults in GED class, equally effective. They really liked "what did I start with?" where I'd write [BOX]+7-2+4-9+6=12 or something and have them try to work out a general method.

Answer 8

They use variables as soon as they start counting. We should introduce number machines ASAP to encourage thinking like a mathematician. The INPUT----> DO ----> OUTPUT relationship diagram is relevant at all levels of Maths and introducing algebra plus x, y graphs is more meaningful. This would also help with the true understanding of the equal sign. I am embarrassed as a maths teacher that variables are introduced in Science to elementary pupils but rarely mentioned in the Mathematics curriculum.