http://www.jmap.org/JMAP_REGENTS_BOOKS.htm
Friday, December 14, 2018
Monday, October 8, 2018
Monday, October 1, 2018
MAT 104_Oct 1_2018_ Matrices Review Videos_Etc.
GAUSS-JORDAN ELIMINATION
Video 1--Start at minute 6
https://www.youtube.com/watch?v=ybQbWYBEZzc
Video 2 is shorter, but I believe video 1 is better and covers what we need for this class
https://www.youtube.com/watch?v=Ff9ba3PryUs
Video 1--Start at minute 6
https://www.youtube.com/watch?v=ybQbWYBEZzc
Video 2 is shorter, but I believe video 1 is better and covers what we need for this class
https://www.youtube.com/watch?v=Ff9ba3PryUs
October 1_Lesson_MAT 103 Videos on Polynomials
CLASSIFYING POLYNOMIALS
https://learnzillion.com/resources/8898/
SUBTRACTING POLYNOMIALS
https://learnzillion.com/resources/9702/
MULTIPLY POLYNOMIALS
https://learnzillion.com/resources/9705/
DIVIDING POLYNOMIALS
https://learnzillion.com/lesson_plans/5835-divide-polynomials-using-long-division/
Wednesday, July 4, 2018
Mathematical Errors in Textbooks
The Misuse of the
Equal Sign in Elementary School and Middle School Division
Consider a typical Division with Remainder lesson. There is sometimes a subtle misuse of the equal sign. For instance, we may see an equation such as 9,317 ÷ 95
= 98 R7. But what does that mean? Let us first consider equivalence relations before picking apart this matter of using 98 R7 to represent the answer to a division problem.
Equality is an equivalence
relations. An equivalence relation R on a set is defined as follows. Let a, b,
c belong to a set S. Then, we define an equivalence relation R on S if the
following properties hold:
11. aRa
(Reflexive Property)
22. aRb implies bRa (Symmetry Property)
33. If aRb and bRc, then aRc (Transitive Property).
Now, let R be equality. Since
middle school math involves rational numbers, let a, b, c be rational numbers.
Then
11'. a
= a (Reflexive
Property)
22'. a
= b implies b = a (Symmetry Property)
33'. If a = b and b = c, then a = c (Transitive Property).
Now, let us return to our division problem.
9,317
÷
95 = 98 R7.
So, let a = 9,317 ÷
95 = 98 R7. Now, using the same representation of an answer we have that
987 ÷ 10 = 98 R7.
Let
987 ÷ 10 = 98 R7 = b.
Then, by the
Transitive Property of Equality,
a = 98 R7,
and we just decided that
98 R7 = b,
in the previous line. Then, by the Transitive Property of Equality, we have
that a = b. But in actuality, 9,317 ÷ 95 =
= a; and 987 ÷ 10 =
= b, showing
a ≠ b. Now, we have that a = b and a ≠
b which is a contradiction.
This issue
of the meaning of equality became a teaching point in this author’s 6th
grade math class. The advice for the students was to use an arrow (à) instead of an equal sign when they
got a remainder in solving a division problem. They would later learn how to
complete the division process to get a decimal fraction instead a remainder.
So, instead of, for instance, 987 ÷ 10 à 98 R7,
students would write 987 ÷ 10 = 98.7, after pursuing a solution
process. The problem with the Go Math textbook is a problem of interpretation
of the Common Core state standards (CCSS). New York’s CCSS 6.NS. B.2 states
that students should be able to, “[f]luently divide multi-digit numbers using
the standard algorithm”
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