Parents: Help your child or teen

Online Volumes (Book Orders)
1,  Elements of Reason. 1996
1A. Pattern Based Reason  1995
1B. Math Curriculum Notes 1996
2. Three Skills for Algebra  1995
3.
_Why_Slopes_&_More_Math_1995

More Site Areas 
1.  Solving Linear Equations  2005
2.-Fractions-Rates-Proportns-Units-2006
3.  Algebra, Odds & Ends, HS level-2001
4.-Euclidean-Geometry/Complex No.s 
5.  Analytic Geometry/Functions 2006
6.  Number Theory. 2006-7
7.  Complex Numbers More 2001
8.  Calculus Introduction 2005
More Site Areas 
9   Real  Analysis 1995
10. Secondary IV? maths 2006-7
11. Math Education Essays  2006-7
12. LaTeX2HotEqn: 2004
13. Electric Circuits Etc  2007
14. Quebec Math Education 2004
15-Prequel-to-the-How-TOs-06-2008
How TOs/ Ref.-08- 2008
1. Arithmetic Reference
2. Algebra 
3. More Algebra 
4. Geometry  
5. More Geometry
6. Calculus
7. Logics in Maths

YOU are better than YOU think. Show yourself  how:

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 In mathematics, sooner or later you need to learn to read like a lawyer. For that  read logic chapters 1 to 5  in  Three Skills for Algebra. Sooner is better. Good luck.

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On the phone with a classmate or tutor,skrbl now
or twiddla  or groupboard to write & draw with each other on art, math & science etc. 


 Logic Mastery
 Amazing, Amusing, Amorous,  Delicious, Delightful, Edifying, Strengthening Elixir. 
It eases work & learning difficulties Makes the hard easier. Opens eyes. Leads to greater precision.
in reading and writing

Do not leave here without it -  Logic mastery  will develops critical thinking, improve reading and writing, and give a firmer base for work and studies at many levels. Good luck.

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Caution: Site advice is approximately correct, for some circumstances, not all. Site How-TOs are logically developed, but not tried and tested. That leaves room for thought and refinement..

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After logic  (a) continue reading Three Skills for Algebra, chapters 8 to 14  and do so alongside site area on solving linear2007 Equations ; or (b) see this calculus starter lesson and Volume 3, Why Slopes  & More Math, chapters 2 to 6;


For online automated help in senior high school maths & calculus, visit  quickmath.com  For Automatic Calculus and Algebra Help with derivatives, integrals, graphs, linear equations, matrix algebra, visit calc101.com  With  overlap, each site quickmath & calc101offers a different range of services, some free, some not, all based on webmathematica. Good luck.

Slopes with Units - Rates of Change

For a straight line graph of a first quantity Q1 versus a second quantity Q2, the slope
m = change in Q1
change in Q2
= DQ1
DQ2
= rise
run
·
The units of the slope m are therefore given by
units of Q1
units of Q2
= units of the rise
units of the run

That is, the units of slope is the ratio given by the unit of rise (vertical axis) over the units of run (the horizontal axis).
Examples of ratios of units that often occur are:
$
kg
,    km
min
,   km
hr
,    miles
hr
,     1,     etc.
Observe that when Q1 and Q2 are measured with the same units, the slope m has no units. It is given by a (real) number. An example follows. The purpose of the unit 1 in the previous list is to be a reminder of this. We may say that a real number has the unit 1 to include numbers in any discussion of quantities. Alternatively, we may say, as convenient, that real numbers are without units. See next example.

Improper Units

The unit 1 is an improper unit. The units  1 radian = 1. So  the degree = [(p)/180] and the one percentage 1.0% = [1/100] are further examples of improper units, that is units that are multiples of real numbers. (The discussion of improper units is unique to this author.

Units in computations have been a concern for chemists and physicists but not so far for mathematicians. The codification of mathematics needs to be extended to include units as a service to other disciplines. 

Cost Versus Quantity -Rates

The metric BWGZ gravel supply business charges the amount
C = $20.00 + w· $15.00
50 kg
for each amount w of gravel purchased. (For each order of gravel, the BWGZ gravel company charges $0.30 per kilogram plus $20.00. The latter could be a handling or order setup charge.) The graph of cost or price C versus the amount w follows.

The slope of this straight-line graph is
m = $15.00
50 kg
= $30.00
100 kg
= 0.30 $
kg
There are several possible ways to write m. Pick the one you like or favor.

For w = 2000 lbs of gravel, the cost would be
C
=
$20.00 + 2000 lbs· $15.00
50 kg
=
$20.00 + 2000 · 15.00
50
lbs
kg
=
$20.00 + 2000 · 15.00
50
lbs
2.2046 lbs
=
$20.00 + æ
ç
è
2000· 15.00
50
· 1
2.2046
ö
÷
ø
$
=
$20.00 + $272.16 = $292.16
since 1 kg = 2.2046 lbs at the surface of the earth.

FOOTNOTE: At the earth surface, a one pound mass and one pound weight are identical measures of material. There is a distinction between mass and weight that has to be considered for calculations away from the earth surface. Students of physics should know why.
In computations, we follow the convention that units can appear before or after the number in it. In contrast, in the presentation of results, the placement of the unit before or after depends on grammatical or cultural preferences of a cosmetic nature.

 


www.whyslopes.com
Fractions, Ratios, Units, Rates & Proportionality

Fraction Starter Lesson
(simplify, multiply, divide & then add or subtract)

An Alternative Starter Lesson 
(take your pick, or try both)


Area Intro
Fraction Starter Lesson A
Fraction Starter Lesson B
1 What is a Fraction
2  Multiplication I
3 Multiplication II
4 Multiplication III
5 Equivalent Fractions
6. Mixed Numbers
7  Comparison
8  Addition I
9 Addition II
10 Addition III
11  Multiplication IV
12  Division
13 Two Term Ratios
14 Implied Ratios
15  Multiple Ratios
16  Units in Arithmetic
16 Longer Explanation
16 Change Units
16 Products of Quantities
16. Fractions with Units
16. Division+Reciprocals
17 Proportionality
17 Examples
18 Rates & Slopes EGs
18 Constant Rate
18 Varying Rate
18 Velocity Calc., EGs
18 Changing Units
18 Slopes and Units
18 Slopes, No Units
19 RealPlayer Videos
Links

Arithmetic Videos - Real Player Format

Decimal Addition
Methods
Decimal Subtraction Methods
Decimal Multiplication Methods
Decimal Division
Methods


Fractions
Primes
Greatest Common
Divisors

Least Common Multiples

Square Root
Simplification


Area Content Summary

  1. Fraction Starter Lesson
  2. Real Player Videos on Operations with Primes and Fractions
  3. Continuous Ruler & Line Segment
    model for fractions and operations on fractions - Number Theory Area points to the general model.
  4. Distinction between Ratios and Fractions, a nuance: While binary ratios a:b may be identified with a fraction, triple ratios a:b:c and further multiple ratios cannot.
  5. Saying how to add and subtract like monomials in units and their powers, and saying how multiply and divide like and unlike monomials leads to fraction like expressions involving units and a framework for discussion rates - ratios of quantities - a framework for handling proportionality constants, and framework for carrying units through calculation in quantitative disciplines

Hint: See site area on solving linear equations to strengthen fraction sense and algebra skills together. Good luck.


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