With my seventh-grade students, I would do transformations, but, depending on context, I would not necessarily expect them to be able to do it.
One time, in particular, that I recall using it is with the distance formula.
For whatever reason, there were many students who knew that r = D/t, and when we started out with problems that required solving for D there would immediately be questions, because their recollection of the formula "didn't solve for" what they needed.
Other students could tell them that D = rt, and I would always do the transformation for them, to show them that the two formulas are "equivalent" before I would show them how to solve the problem both ways.
I always found it fascinating that the students often had no problem understanding how to solve the equation (once the values were plugged in), but they were totally confused by the transformation, using the variables.
-----Original Message----- From: email@example.com To: firstname.lastname@example.org Sent: Sun, 28 Jan 2007 10:55 AM Subject: [math-learn] Transforming formulas
In math and physics there are many formulas. Some of these formulas are main formulas and other are derived. For example, formula A=a*b (for area of rectangle) is main formula and formulas a=A/b and b=A/a are derived formulas. Transforming of formula A=a*b into derivated formulas isn't so complex, since formula A=a*b isn't complex. But, we (in math and physics) have many formulas which are not so "trivial". For example, formula for perimeter of rectangle is P=2a+2b, area of triangle is A=a*h/2, area of trapezium is A=(a+c) *h/2, etc. Transformations of such formulas are much complicated.
Do you teach your students how to transform formulas? Do you teach it just for some special cases or more generally? When (in which class, with which age of students)?
All comments very welcome!
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