Other Does it matter if I forget the formulas?

1. Oct 21, 2017

Apple_Mango

I forget the formulas I learned after a few weeks. I was wondering if it matters if I forget the formulas. Should I really have drilled the formulas into my head and remember how to do every single one?

2. Oct 21, 2017

Staff: Mentor

Then you didn't really "learn" them.
For some formulas, it really matters. For example, the distance formula and quadratic formula should be memorized.
It would help if you tell us what formulas you're talking about.

3. Oct 21, 2017

symbolipoint

One learns which formulas must be memorized and which may later be searched for in reference materials.

4. Oct 22, 2017

Staff Emeritus
This.

In previous messages, you've discussed trying to whip through the material and skipping courses. Mark is right; if you can't remember them weeks later, you didn't really learn them.

5. Oct 22, 2017

symbolipoint

Which formulas do you not remember? Do you need them for your work from one course to another? Those you do, you need to remember as well as to understand.

6. Oct 22, 2017

Dr. Courtney

At some point, many formulas can be derived from other more fundamental formulas, definitions, and principles. But usually, students don't have the time or mastery to do that yet when the formulas are needed (as on an exam). For example, all the kinematic equations follow from the definitions of velocity and acceleration and the assumption of constant acceleration. But the quickest way to derive the formulas requires Calculus, and most students find it easier to memorize them than to re-derive them under time pressure.

There is also an important difference between more fundamental formulas that apply in a wide range of circumstances and more specific formulas that only apply in a narrow range of circumstances. For example, the kinematic equations apply whenever the acceleration is constant. They are often used as a starting point in solving projectile motion and other kinematic problems. In contrast, the range formula is an intermediate result that applies to give the range of a projectile whose final height is the same as the starting height. It is more of the answer to a problem than the starting point. There is much less need to memorize less fundamental formulas like the range formula.

I often see students trying to memorize formulas for solutions to Atwood machines in various configurations. This is silly, because the odds of remembering the right formula for a wide variety of configurations is slim. The needed formula is Newton's second law and possibly the kinematic equations.

7. Oct 22, 2017

Tio Barnabe

No.

The most important thing is to learn the theory. Once you learn it, you should be able to derive the equations, or "formulas", from the theory. That doesn't work, however, for the cases where the equations are empirical or follow up from postulates/principles.

8. Oct 24, 2017

Apple_Mango

Perhaps I should had specified more details in my post.

A few weeks after I did my first exam, I find myself not remembering some of the formulas I did from my first exam. I think I can remember the formulas again if I had the formula sheet. I was wondering if it matters if I forget the formulas I did from my first exam? For instance, I don't remember slope formula. Is there really a point in remembering the formulas if I can use the formula sheet to refresh my memory?I find it mind boggling to remember every single math formula.

Last edited by a moderator: Oct 24, 2017
9. Oct 24, 2017

Apple_Mango

I do not understand what you're saying. I am just in Algebra 1. I don't understand those terms you're telling me.

Last edited by a moderator: Oct 24, 2017
10. Oct 24, 2017

gleem

Just to clarify your OP what course are you referring to and could you give examples of equations that you are forgetting.

11. Oct 24, 2017

Dr. Courtney

Reader's Digest version: If you cannot derive it, then you should memorize it.

12. Oct 24, 2017

Staff Emeritus
Yes, that is a problem.

13. Oct 24, 2017

symbolipoint

You need to both understand AND memorize certain formulas. Educators put certain formulas onto formula-sheets for test-taking purposes, especially if rederiving them will be too time-consuming. Some formulas you MUST memorize for Algebra 1 are slope of a line, slope-intercept equation of a line, standard form equation of a line, factorization for quadratic trinomial, factorization for difference of two squares; possibly a few others. You may need to know how to work your way through constant-rates formulas of the form k=y/x which may be applied in the form, y=kx.; handling the units of measure often hints at how to arrange the variables.

Later, in such courses as College Algebra, Trigonometry, Calculuses 1,2,3,4, any Physicses or Engineerings, you still must keep memorized those same things, AND MORE.

14. Oct 24, 2017

I like Serena

I consider blindly memorizing formulas to be generally useless. Better look them up if that's all we do.
Understanding where they come from (make a drawing!), and practicing with them is how we learn them.
As a side effect we may actually be able to write down such a formula without looking it up, or deriving it again, which is nice since it means we can use them quicker and easier.

Then again, I guess we're talking about teaching methods here?
As a teaching method we can start with blindly memorizing, and to try to get to understanding later.
Either way, it means that the memorization is just an intermediate step.
If we forget after a couple of weeks, we can just memorize it again, and again, until understanding dawns one way or another through practice.
Then there won't be a need to memorize it again.

15. Oct 24, 2017

symbolipoint

The discussion seems to be both teaching and studying/learning. Formula understanding must go along with memorization, especially at the level of Algebra 1 (as Apple_Mango gives for his current course).

Blindly memorizing, I would suggest NOT to do. The necessary formula needs to be taught, including derivation if can be done. A definition can just be explained and then expressed, and re-explained.

16. Oct 24, 2017

Staff: Mentor

That's not "remembering the formulas" if you have the sheet of formulas in front of you.

For the class you're in, that's a problem. Graphs of straight lines are the simplest kinds of graphs. If you are given two points on a line, you should be able to find the slope of the line, without having to look at a sheet of formulas.

17. Oct 24, 2017

symbolipoint

Does it matter if you forget the formulas?
In short, YES.

Picture yourself in a real-world working situation.
You need to know the density of a liquid. You find that at 80 degrees F, it is 1.01 grams per ml. You cool the liquid to 55 degree F and it is 1.13 grams per ml. You NEED to know its density at 68 degrees F. What can YOU do?
• Make a graph on paper and plot (55, 1.13) and (80, 1.01); and draw the line through the two points; and now, read the coordinate for 68 degrees F.
• Use the two data points to form and simplify a linear equation for density as a function of temperature; and use this to compute what you need (like, x=68; find y).
• Use simple linear interpolation to find what is y , having (55, 1.13), (68, y), (80, 1.01).

Most of that is what someone who learned Algebra 1 can do.

18. Oct 25, 2017

Staff Emeritus
I never advocated blindly memorizing anything. But if you are taking algebra and can't find the slope of a line without a sheet in front of you, it's hard to argue you really learned the material.

Last edited: Oct 25, 2017
19. Oct 25, 2017

"Never memorise something that you can look up" ................................................ Einstein

However that is not necessarily good advice for a student. It's important to understand the equation and to know their limitations, if any. Also you need to be competent at applying the equations so practise using them.

It can be an advantage if you memorise the equations, particularly when it comes to exams. My advice is to make a list of every single equation you need for a particular course. You may find that the list of equations is not very long. Make sure that you understand every equation. Next, write your equations up neatly and stick your list(s) on one or more walls somewhere, for example on a bathroom wall. You can now take a quick look at the equations every time you visit the rooms.

20. Oct 25, 2017

Apple_Mango

I disagree. If one didn't learn the material, then one wouldn't be able to do solve the equation in the first place.