Math - do you force memorizing geometric formulas?

[Blossom'sGirl]

Oldest ds is almost finished with the Auffmann Pre-Algebra book. Today he took the test for the geometry section, and when I went to correct it, I noticed that there were no formulas written and no work shown. I have been telling him to SHOW HIS WORK forever and it is so annoying that he didn't. Anyway he walks off with his test (I told him to fix it) and the formula sheet from the back of the book. I never said he could use it. Am I being unreasonable that these should be committed to memory? I know when I went to engineering school we were allowed formula sheets, but this is basic geometry. I think the most complicated formula is the area of a cone.

 

I informed him that he will be retaking the test on Monday and that no formula sheet will be allowed.

 

He is going to start algebra in January, but I need an improved attitude.

[Dana]

I'm forcing it at my son's age (9).

If work isn't shown, he doesn't get full credit on tests.

I view it as teaching communication. In English, we write in complete sentences with grammar and mechanic conventions. Math has its own conventions.

 

I want understanding as well so he can derive some of the formulas if he forgets them, but I view memorization as an important step as well.

[kiana]

Re: Showing work.

 

On higher level exams, if the answer is correct w/o work and it's something I can do in my head, I give the marks. If it's incorrect w/o work, it gets a 0. If it's incorrect but I can see that the work was correct and a careless error was made, partial credit.

 

This is a sufficient inducement for most.

[LauraQ]

Well, I would help him learn *why* the formulas work and how you can figure out the formula by thinking through the problem so that if he ever doesn't have a formula cheat sheet he can figure it out on his own. Formulas are easy to forget or remember just a little bit wrong, but if you understand the how's and why's of the formula, you're more likely to be able to reconstruct it later from memory. Of course, that's a bit much for Pre-Algebra. But it's something to keep in mind as a major goal for when he takes Geometry later on.

[Jann in TX]

In Pre-Algebra Geometry is used to PRACTICE using formulas... instead of giving 'generic' formulas they happen to use ones the student will see in a few years. The goal is to USE formulas --not memorize them.

 

Most students will naturally memorize Area, Perimeter and Circumference... these are often introduced in elementary texts..

 

The second semester of a HIGH SCHOOL Geometry class is formula work--MULTIPLE CHAPTERS -- with each chapter focusing on one particular type of formula.

 

I would NOT make a Pre-Algebra student memorize (in one chapter) what will take a high school student one full semester to learn...

 

My Pre-Algebra students will be allowed to use a formula sheet (as needed) on their tests. My Lial's BCM students have a single chapter on Geometry-- formula sheet is definitely used! My Lial's Pre-Algebra students have a little Geometry in each chapter... they will/can have access to the formula sheet (inside cover of text) but most will have a good working memory of the formulas needed for that chapter (only a few at a time).

[Blossom'sGirl]

Thanks Jann for the voice of reason. I haven't corrected his test yet, but I already took him aside and informed him that I overreacted to him helping himself to the formula sheet and that next time he is to ask me first. I told him he will not need to retest on Monday if this one is good.

 

I will still be a stickler for showing work, and I plan on taking some points off for me having to remind him.

 

He was looking up the formula for a trapezoid.