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Appetizers and Lessons for Mathematics and Reason   reviews of www.whyslopes.com,   
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: www.whyslopes.com   a 1200 page website   words for teachers      
 Français : Algèbre  Définition d'une variable   La raison basée sur les  règles et modelés


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1. Arithmetic How-TOs
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3. More Algebra How-TOs
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Vol 1, Elements of Reason

Proper notation & format 
makes the hard easier.

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20 pages in French: Algèbre  
Définition d'une variable
  
La raison basée sur les 
règles et modelés

Volume 1A
  Pattern
Based
Reason
 
1995-6

Chapters: benefits, origins and limits of  rules & patterns in daily life, business   technology.& science. Not all is certain.

Volume  2
  Three Skills
for
Algebra
1995-6

Chapters: starter lessons for logic and algebra 
Appendices:  Advice and Directions for Students

 Volume 3
Why Slopes 
and
More Maths
1995-6

Chapters: starter lessons for differential & integral calculus  Appendices: starter lessons for real analysis -  for a few.

Volume 1B.
 Mathematics
Curriculum
Notes
1995-6

Foreword:  Principles for progressive skill development. Chapters:  Olde Gaps in Course Design 

For:  Law, mathematics, science, engineering students & their teachers. For: Adult mathphobics, Avid Readers in school or out;   Calculus & Gifted High school Students.  Chapters For:  Calculus & Gifted High school Students. .Appendices For: Math, Electrical Engineers & Physics Undergrads. For:  teachers, parent school committees, mathematics education committees

 Paperback versions of site books (online in full)  are  available for gifts or  for offline reading.

Welcome. In 1200 pages, online books and further site areas (below and right margin) offer end, values,   lessons or lesson plans for mathematics and logic from the last years of primary school to the first year of college or beyond.  Site material is often addressed to learners or general reader, but the readers most wanted are mathematics instructors and curriculum designers.

Help Elsewhere for Students: Three text-based sites  mathsisfun purplemath and themathpage are well-done.   The BBC also provides help (examples) in: mathematics and many other subjects for students.   The  Khan Academy has over a 1000 UTube videos on  mathematics etc. The Bright storm Flash Video Site:  (it requires a membership) for secondary  mathematics US style and some calculus lessons with an emphasis on the mechanics (the how, not the why), Brightstorm flash videos are neat and usually well-done except for notational lapses - doing calculations in place instead of doing one step per line, one step after another.  

 The following site reviews follows describe site content - its value and its limitation 

The NSDL Scout Report for Mathematics, Engineering, & Technology -- Volume 1, Number 8 (May 24, 2002) Site Description: Math resources for both students and teachers are given on this site, spanning the general topics of arithmetic, logic, algebra, calculus, complex numbers, and Euclidean geometry. Lessons and how-tos with clear descriptions of many important concepts provide a good foundation for high school and college level mathematics. There are sample problems that can help students prepare for exams, or teachers can make their own assignments based on the problems. Everything presented on the site is not only educational, but interesting as well. There is certainly plenty of material; however, it is somewhat poorly organized. This does not take away from the quality of the information, though.

Better organization of site material will follow reflection on what should be here to help learning and teaching. 

Bon Appetite.  Each site element is different. If one is not to your liking, try another. 

A Visit to typical Guidance Office

"Would you tell me, please, which way I ought to go from here?"
"That depends a good deal on where you want to get to," said the Cat.
"I don’t much care where--" said Alice.
"Then it doesn’t matter which way you go," said the Cat.
"--so long as I get SOMEWHERE," Alice added as an explanation.
"Oh, you’re sure to do that," said the Cat, "if you only walk long enough."
(Alice's Adventures in Wonderland, Chapter 6)

Site elements mostly likely to help

  • Logic chapters 2 to 4 in Volume 2 may sharpen wits and improve reading and writing skills for work and study. Start with chapter 2. Logic mastery will help you follow and question ideas more sharply.  With logic mastery you may blame explanations and not yourself for lack of understanding. With logic mastery you may be able to understand the small print in contracts and in instructions in work and studies..

  • Ends, values and methods for work and study - Read these for yourself or recommend them to others.  The advice and values here will improve and speed your work and studies - make you more appreciated, we hope. 

  • Fractions - see how raising terms not only leads to addition, subtraction and comparison methods for fractions, but also for multiplication and division.  This implies a re-arrangement of senior primary and junior secondary mathematics in classes where teachers and students are both receptive to seeing why those methods work. 

  • Solving Linear Equations with stick diagrams, then without, followed by solving simultaneous equations in essentially one unknown points to an acceleration of junior secondary mathematics, immediately useful. The pathway for this is likely to be effective with secondary school and older students. 

  • Forward and Backward Use of Formulas. Talking about this expresses in words a theme very present but silently so in high school and college mathematics and science courses. This illustrate a unifying theme that high school and college teachers may employ immediately without changing course.   Indeed every rule and pattern in mathematics, logic and science will be used not only directly, but also indirectly 

  • Euclidean Geometry - This simple introduction which employs implication rules directly, an introduction that is sufficient to illustrate the role of logic in mathematics and to provide a deductive foundation for the further study of right triangle trigonometry. (An alternative foundation based on common assumptions about maps and coordinates  appears in the site section Maps, Plans,  Similarity & Trig,)

  • Complex Numbers - see how a full and logically complete geometric explanation is possible before the discussion of unit-circle trig begins.  This implies a re-arrangement of senior high school mathematics that will unit circle trig and trig formulas in 2D vector studies easier to explain.  This development is likely to see service first in senior high school mathematics and in college studies in mathematics, science and engineering.  Why this path was not employed earlier in secondary mathematics is a bit of mystery.  Answering why is left for later. 

  • This fall 1983 lesson and chapters 2 to 6 in Volume 3, Why Slopes & More Maths, show Why Slopes are studies,  why polynomials are factored, while giving a preview  or starter lessons for  calculus. The previews here may be employed to provide motivation for studies before calculus - those covering slopes and factored polynomials. 

  • Functions - Forwards & Backwards - The set and rule-views of functions and relations are cleverly combined here not to emphasize the set theory development of mathematics, but to provide an operational command of function concepts needed in calculus. Explanations and notation should aid comprehension and skill mastery, and not be overwhelming. 

Two Gaps

What is a variable?

"When I use a word," Humpty Dumpty said in rather a scornful tone, "it means just what I choose it to mean -- neither more nor less."
"The question is," said Alice, "whether you can make words mean so many different things."
"The question is," said Humpty Dumpty, "which is to be master - - that's all."
(Through the Looking Glass, Chapter 6)

Would you believe there needs to be a greater role for more geometry and then words in the introduction of algebra? In you versus algebra, there is also question of who will be the master?  Site areas on solving linears equations and Volume 2 are both voting for you. 
  1. The olde Algebra Gap:  The shorthand roles of letters and symbols  are not fully explained or rationalized from solving equations to the very challenging use of algebra in advanced mathematics (calculus).    Solving linear equations starting with fractional operations on stick diagrams gives an entry level, geometric introduction to algebra with letters referring to visible lengths.   Chapters 8 to 12 in Volume 2  and the essay What is a Variable put more words into the explanation and comprehension of algebra.   Chapter 14 in the same Volume 2 with its  detailed discussion of the direct and indirect use a formulas identifies a unifying theme for algebra and logic - all rules and patterns  may and will be used forward and backwards in mathematics, science, technology and logic or reason. The very challenging use of algebra in calculus is made easier by (i) this  why slopes, geometric preview of calculus, by (ii) this factored polynomial, algebraic preview in  Chapters 2 to 6  in Volume 3, and by (iii) the further discussion of slopes, limits, derivatives and integration  in Chapters 11 to 18 of Volume 3. Mathematical Fact:  Calculus requires earlier high school mathematics and logic at full strength: (i) This  long  complex numbers lesson on  shows how to simplify the development of periodic trig functions, the derivation of their properties,  and the derivation of trig identities and formulas in the plane  for vectors dot and cross-products.   For further algebra skill development, see the site coverage of fraction with units, proportionality polynomials, quadratics functions  and straight line slopes and equations.  And for logic mastery, start with the math-free chapters 1 to 5 in Volume 2 as early as possible for the sake of precision or greater precision in reading, writing, reason. 

  2. The New Arithmetic Gap: An exact and efficient mastery of arithmetic with decimals and fractions is needed for proper, full strength,  high level  study of mathematics alone and in science, technology and business.   In site material, webpages  with html, and real player and flash format  webvidoes on arithmetic with decimals and integers,  on  fractions and solving linear equations with fractional operations on stick diagrams may help fill this gap.  Calculators and computers (cash registers too) can be and should be employed to do arithmetic. But the exact and efficient command of arithmetic  should be obtained in the last years of primary school and the first years of secondary school, partly to serve these ends, values & methods for work & study - learning to avoid  mistakes in  multi-step methods via the early  mastery of exact arithmetic with decimals;  and partly to set the stage for an exact and careful mastery of algebra.  The division of polynomials (a requirement for calculus) will be easier for students well-practiced  long division with whole numbers (decimals).  Before skills and concepts are de-emphasized, course designers need to have a technical  knowledge of skill and concept dependencies, and what happens to later skills and concept development  when earlier skills and concepts are not covered.  Quantitative skill development should reflect a critical path analysis and knowledge of the ends, values and methods of instruction which have been

Skill & Concept Development Pathways

For Instructors:  Outline of a new Applied Math program K5-12.  Lamp an earlier program.  Mathematics education essays

  Grades 5 to 9 Grades 8 to 12 Pre-Calculus and Calculus
Decimal Methods (for counting, comparison, addition, subtraction, multiplication and long division) . Forty Flash Videos, The Forward and Backward use of formulas (also rules and patterns) is  a unifying theme for senior high school and college mathematics and science.   The theme appears here with the compound interest formula. In retrospect ( a site or teacher to do),  simpler formulas introduce the theme. In handling Proportionality Relations, forwards and backwards, this theme appears with backward use (obtaining the proportionality constant) often put first.   The forward and backward of formulas and rules is very present part of logic (see contrapositive),  of basic to advanced mathematics from algebra to calculus, and in advanced  science courses. Repeatedly talking about direct and indirect use of formulas will bring the fore a common but hitherto silent practice  Essay What is a variable  puts words before and beside symbols at a level the calculus or precalculus student will understand.  Fellow Mathematicians: Arguments against past verbal descriptions of variables do not apply here.  Ages 14+ and before calculus.
Integers:  12 lessons and three appendices to provide a thought-based understanding of operations and properties.  12 Flash Videos Wordy Introductions to Logic may develop precision reading and writing needed in maths, all further studies, home life and work for better performance or self-protection  - Romeo and Juliet make mathematical induction easier to understand and explain - Chains of reason provide a model for reason in Euclidean Geometry  outside mathematics. (Ages 15+  but  earlier for avid readers, gifted students).
More Arithmetic with Signed Numbers not only for integers, but also for fractions and real numbers.  A do-this, do that approach
Fractions - A full  thought-Based Development. - seeing how raising terms justifies not only fraction  addition, subtraction and comparison methods but also fraction multiplication and division method.  
Basic Number Theory  
Primes & Composites
+Primes & Composites + Prime Factorization Examples + Counting  Whole 
No.  Factors
+ Prime Factorization Aids + Square Roots  & Prime

More Number Theory
Fractions as Decimals1 = 0.999 Recurring +
Infinite Decimals Expansion Arith + Ratio of Simple FractionsRatio of Decimal Fractions

Three Skills for Algebra (Talking about Numbers, Describing Calculations, Describing when calculations are equal, what is a variable) may ease or avoid  fears & difficulties and clarify concepts that obvious to some, but not  ALL. The algebraic way of writing and reasoning needs to be introduced with words - rationalized.   Ages 14+ Powers, Roots and Logarithms
(i) Algebraic theory of Exponentials, logarithms and roots (radicals)
(ii) Natural Logarithms, Exponentials, and logarithms for arbitrary bases.
(iii) Powers with Real Exponents - From Roots and rational powers of positive numbers to real powers of positive numbers. Here are definitions which calculus students should see. 
Back Ground Information Only:  Ratios And Fractions (or ratios versus fractions)   a thought-based development to emphasize similarities and differences. Analytic Geometry of Straight Lines in the plane: slopes, intercepts, various forms of equations, properties.  A treatment with theory.  In a sense, this is application of the ability to solve linear equations in 2 unknown numerically or literally. Function Theory (complete) for Senior High School and Calculus Students - Multiple Viewpoints explained and reconciled.  Ages 15+.  May begin before and finish in calculus. Emphasizes function theory leanly   Sets appear here, but only as a tool to further  the development of function theory or definition.  practices for real functions y = f(x) of a single variable.  Instead of talking about horizontal and vertical line tests, we talk about horizontal and vertical line methods for calculating a function from a graph or set of points in the plane. 
A Geometric path for algebra skill development

Solving Linear Equations 
ax+b = cx+ d with stick diagrams - where x or another letter denotes an unknown length - one that can be drawn.  Solution follow from fractional operations on line segments may introduce students to solving linear equations without stick diagrams (Next topic)  and also reinforce fraction sense and skills. Adopt the  three column format to provide an example of how following a format allows steps to be done and recorded, one at a time, one after another in an observable manner.   That give a model and a standard for showing work. 

Solving linear equations.  Solving Linear ax+b = cx+ d without  stick diagrams where the letter x may denote an unknown number, one that cannot be seen, rather an unknown length, one that can be seen. The format used and advocated  here also appears in .purplemath.com  coverage of the same topic .  The format show students how to do steps in an observable and verifiable or correctable manner. A second reason for the format is its resemblance to a format use later in (a) solving systems of equations in two unknowns; and in  (b) the statement of rules for manipulating equations - obtaining equivalent ones.  

Enrichment:  Chapter 15 of Volume 2 begins with  examples of a repetitive kind  and  goes further. It introduces the algebraic (literal) solution of equations in a step-by-step manner.  U may like it. 

Solving  Simultaneous Equations in essentially one unknown.  Many  elementary  word problems in junior high school require students to find and express all quantities in terms of  one unknown - the essential unknown - in setting up a linear equation in that unknown . But the linear relations in such problems may more readily be written as simultaneous equations in two or more unknowns,  simultaneous equations likely to easily recognized as having essentially one unknown.  The foregoing kinds of word problems can be made simpler by showing students how to solve simultaneous equations in essentially one unknonw. That is 

 Solving  Simultaneous Equations in the other easy case, the  "triangular or diagonal" system case, where no elimination is needed, may serve as a prequel to solving simultaneous equations by elimination.  




Senior High School Topic:  Gaussian Elimination for Simultaneous  Linear Equations

(i) )  substitution method for systems of Equations in two unknowns  The substitution method met in solving equations in essentially one unknown sets the stage for rewriting linear equations in essentially one unknown form or in triangular form.   

(ii) Two More Forms of Gaussian Elimination   (a) comparison and (b) Equation (or Row) Addition,  Subtraction and Multiplication.  The comparison method leads to one equation in one unknown to solve..  The Addition etc method leads to a triangular system to solve. (Examples or further examples are given  in the Making Triangular Section of  Chapter 15 of Volume 2, Three Skills for Algebra . The chapter ends with an example of triangularization of a system of equations in 3 unknowns via the addition etc method.

Fractions with Units: Arithmetic and Algebra with units for chemistry, physics and ordinary mathematics students. Here is context for  develop skills with monomials and their ratios with units of measure in place of variables.
Four Operations on Polynomials, A quick, informal approach.  The approach is justified for polynomials with in non-negative variables with non--negative coefficients. But it provides patterns to follow in the general case where the foregoing conditions are relaxed or not checked.  In any event, the full blown rigourous development would overwhelm students. 

Calculus Preview or Starter Lessons: Geometric  and Algebraic (Chapters 2 to 6  in Volume 3) Calculus Previews:  These offer an end earlier studies or a start for calculus in a manner that strengthens algebra skills and so  eases or postpones calculus difficulties. The Geometric preview explains why slopes are studied - and led to the title of Volume 3 and the site domain name. 

Quadratics:  Graphing, Arithmetic and Algebraic Approaches to Factorization. Derivation of Quadratic formula from completing the square, difference of two squares.  The algebraic way of writing and reasoning is employed at full strength in calculus.  The aim  again is to make the algebraic process more accessible. With the previous steps for algebra ability development, that might just be possible.  For Enriched or Advanced Calculus: Epsilonics - mentioned by often skipped in first courses in calculus. :  Chapter 14 in Why Slopes and More Math  introduces and provide a context for epsilon-delta view by giving the numerical analyst view of error control in limit and function evaluation or calculation.  Where modern maths tries to skip the mention or use of decimals, numerical methods in calculus and in advanced studies of applied mathematics depend on decimals. We leave college course designers to reconcile that discrepancy.The decimal representation of real numbers with limits and convergence related to the possibility of unlimited error control (decimally described)  in the evaluation of functions and limits might make epsilonics easy for undergraduates specializing in mathematics or advanced students of calculus/real analysis

Basic Logic Difference between A if B and A if and only B. Use implication rules, one at a time, one after another, mathematical induction  - a Romeo & Juliet version

Optional Reading: Painless Theorem Proving. 

Euclidean Geometry (Basic Elements, 
Uses Direct logic only)

Correspondence
Isometry
Side-Side-Side
Bisecting Angles
Side Angle Side
Angle-Side-Angle
Isoceles
Right Bisector Construction, Etc.
Perpendicular - Point to Line
SSS Failure
SAS Failure
ASA Failure
Parallel Lines
Angle Sum to 180 in triangles

For all calculus students - more from chapter 14: Evaluating Limits for Derivatives Algebraically -  three examples of a limit depending on different values of x  followed by identification of  recognition of a common pattern. The example here is key to thinking of the derivative as a quantity which depends on x.  Following that, we may switch from calculating derivatives for one point at a time to calculating derivatives over intervals  in the real number line.  The Chapter ends with several webvideos of derivative calculation.
Square Dissection Proof of the 
Pythagorean Theorem - Geometric & Algebraic

Preparation for Right Triangle
Trigonometry and Vectors

  Similarity
Right Triangle Similarity
  Trig  or Similarity
Parallelograms
Kites From Triangles Duplication
  Parallelogram from 
  Triangle Duplication

Modular or Remainder Arithmetic for real numbers - needed in the study of circular trig functions.
What is a Derivative? Saying how to calculate a function or a quantity directly (that is best) or in the limit defines it.  Chapters 15 in Why Slopes and More Math   talks about calculating slopes or derivatives for  nonlinear functions by limits. But there is a twist in calculus:  We use limits to provide a first way to say what a derivative is and practice calculating derivatives with the aid of limits. But then we switch to algebraic methods which allow derivatives to be calculated from the algebraic form of a function or a formula for it. 


Complex numbers & properties introduced geometrically & rigorously before the development of periodic trig functions will simplify  simplify the high school level 2D geometric development of   trig and  vectors.  The simple geometric proof here of the distributive law is the key. The advantages of using complex numbers in the exposition of trig was well-known in the 1940s or earlier.  Easy consequences of the complex number approach for (A) f trig identifies (well-known) and for (B) developing trig formulas for dot -an cross-products in the plane are included.  So here is an option for modifying and enriching courses covering unit circle trig and  vectors.

Why complex numbers were not geometrically developed before trig in the course designs of the 1950s or 60s is a bit of mystery.  Some inquiry or research may explain why.  Since 1976, this site author looked for a simple proof of the distributive law, found or re-invented several, only to learn in February 2010 that giving a geometric proof was an exercise in Secondary Mathematics, A Functional Approach for Teachers, H. F. Fehr,  D. C Heath and Company Boston 1951=

What is Velocity?  Saying how to calculate a function or a quantity directly (that is best) or in the limit defines it. In Chapter 16 in Why Slopes and More Math  By graphing distance versus time in the plane, we may use a limit to say what is a velocity.  Given a formula for the distance, you may apply the algebraic differentiation rules in place of limit calculation rules to find formula for velocity.  
What is Area of a region or the Area under a curve y =f(x): Saying how to calculate a a quantity directly (that is best) or in the limit defines it. Chapter 17 in Why Slopes and More Math introduces  limit process to say or suggest what area should be. That definition may be used in calculus 

 

 



About  Pattern Based Reason

This online Volume  surveys rule and pattern based thought in daily life, society, science and technology. The first chapters  show how reliable implication rules can be employed one at a time or one after another to arrive at conclusions. The middle chapters r survey the origins, discovery and applications of rules and patterns. Not all is certain. The problem of identifying reliable knowledge is described, but not solved, except for an explanation of the empirical method of coping. The identification problem touches many subjects. Students of critical thinking, persuasion, philosophy, mathematics, science and technology should find its discussion helpful. The last chapters in this book show how the common concepts of a rule being obeyed, disobeyed or not disobeyed may justify provide a context for the entries in truth tables .

About Three Skills for Algebra

This work begins with logic and then introduces algebra.  Logic, that is a mastery of rule- and pattern-based reason is needed in all disciplines. In particular, it may lead to precision reading and writing. If you cannot read precisely, how will you understand and how will you see errors in your own work or that of others. The first chapter on logic or rule-based reason shows the difference between one- and two-ways implication rules. Not seeing this difference is a source of confusion. Seeing the difference is a first step towards the better understanding of the implications, suggestions, rules or information met in daily life, at work and in school or college. The initial chapters on reason  talk about chains of reason, about islands and divisions of knowledge and about longer chains of reason. Altogether, the  logic chapters provide a  unique mathematics-free introduction to the direct and indirect definition and rule-based thinking that appeared in Euclid's work a long time ago (2300 years ago)

Three Skills for algebra are as follows.

  1. We can talk about numbers and quantities. The words or adjectives used here may be used in mathematics after arithmetic.  There is more to mathematics than just doing arithmetic.
  2.  We can describe calculations that might be done (or postponed) with words alone or with an (algebraic) shorthand notation. The description of calculations that might be done is also part of mathematics after arithmetic. There is more to mathematics than just doing arithmetic.
  3. We can change the way a number or quantity is computed. Some rule-based reason is required here. There is more to mathematics than just doing arithmetic.

The first skill, talking about numbers and quantities, use words to describe them, gives a unique comprehension of numbers and quantities apart from but parallel to the the shorthand role of letters and symbols in mathematics.  The separation here  is needed for a clearer, more precise understanding of  the shorthand, symbolic, way of writing and reasoning that we call algebra.  In retrospect a fourth skill for algebra, Forward and Backward Use of Formulas,  is introduced in chapter 14. 

The objective of this volume and the next is to complement other texts in algebra, trigonometry and calculus. Students may be able to read the first part of this book during their high school days and keep the rest of this work for consultation during their college studies. Material elementary to advanced is covered.

About Why Slopes  & More Maths

The why slopes chapters extend this tour and provide a geometric motivation for calculus, easy to describe and to repeat without a great dependence on algebra and without requiring a mastery of the rules of differentiation, that is slope calculation, for nonlinear functions. The first why slopes chapters gradually illustrate the algebraic or symbolic way of writing and thinking. The later is employed more deeply in some later chapters and at full strength in proper calculus courses. The aim of the first chapters is to provide a simple image-based preview or review of calculus. In it, dependence on symbols or algebra is kept to a minimum. The images may help readers to see and physically grasp the simplest slope-related ideas in calculus. The remaining chapters cover more topics  Appendices present the most advanced topics. Theorems in first courses on calculus are often stated without proof. The appendices state the theorems and give or indicate the proofs. This should provide a context for the decimal-free approach favored in advance calculus or modern mathematical analysis.

About Fractions 

Most likely you have seen how raising terms permits the addition, subtraction and comparison of fractions with unlike denominators. But have you seen how that works for division for fractions with unlike denominators.  Recall or note products of fractions are easily done when the numerator of a second factor is a multiple of the denominator of the first. When that is not the case, we may raise terms in the second factor to obtain that case.  Whence multiplication become easy.  The skill development paths may help in senior primary and junior secondary mathematics. The use of equal signs and their vertical alignment is emphasized here to show how to do and record steps in an observable and verifiable or correctable manner. 

About Solving Linear Equations

We introduce this topic not with unknown & invisible numbers denoted by letters, but with unknown and visible lengths, and obtain solutions by fractional operational operations on line segments.  A three column format is emphasized here to show how to do and record steps in an observable and verifiable or correctable manner, and also to show how solve linear equations apart from fractional operations on line segments.    The column format suggested here for solving linear equations algebraic is chosen to  show how to do and record steps in an observable and verifiable or correctable manner. A format for checking solutions is also included so that solvers may know whether or not their work needs correction before grading.  We tell student if the check fails, the error in their work lies between the start of the solution and the end of the check. Note: The format chosen for solving linear equations in one unknown provides a mechanism for taking terms to the other side  in a just do it, silent manner.  This format is chosen  not only since it shows how to do and record steps in an observable but also as  its resemblance to later methods for solving linear equations in two unknowns.  The format here 

 Basic word problems in junior high school are often equivalent to systems of equations in essentially one unknown.  We explain here how to solve such systems via substitutions that lead to one equation into one unknown - the case previous studied. Those substitutions in the more complicated require an operational mastery (but not the formal statement) of associative and distributive properties of rational numbers. The formulation of basic problems as system of linear equations in essentially one unknown has the advantage of avoiding mental gymnastics in identifying the essential unknown, and in the process points to the power of algebra to solve some problems easily.   All the foregoing sets the stage for the next steps of solving triangular of equations directly and solving systems of equations by Gaussian elimination, or equation addition and multiple methods may 

About Forward & Backward Use of Formulas 

Talking about this expresses in words a theme very present but silently so in high school and college mathematics and science courses. This illustrate a unifying theme that high school and college teachers may employ immediately.   Indeed every rule and pattern in mathematics, logic and science will be used not only directly, but also indirectly.  And in the study and use of proportionality relations, the backward use may appear first in the process of finding proportionality constants.

The Three Skills for Algebra coverage of compound interest and related matters is part of the preparation for calculus.  But it may also may be part of the money matter quantitative skill development that every citizen needs for self-defense. 

About 18. Maps, Plans,  Similarity & Trig, (alt view)

Learning how to use and make maps and plans with the same scale in all directions could be a late primary school or junior high school study with take home value for construction and travels. Implicit in that use are notions of like or similar shapes, and distorted shapes and angles. Map and plan usage and drawing represents a practical self-contained mathematical topic which should be explored to the greatest extent possible years before the introduction of trig and any thought-based development of Euclidean geometry

About Complex Numbers

The geometric and visual perspective of these numbers may be introduced with or after rectangular and polar coordinates in a junior or senior high school course.  We may show that  polar coordinate based rules here for multiplying and dividing points in the plane is consistent with the law of signs for multiplication and division of real numbers. The development here is clear and understandable before the introduction of periodic trigonometric functions.  It is mathematically correct modulo the level of rigour usually met in the explanation of the latter. This implies a re-arrangement of secondary and college courses that will make unit circle trig and trig formulas in 2D vector studies easier to explain.  Why this path was not employed earlier in secondary mathematics is a bit of mystery.  Is the development here of complex numbers and its easy consequence simple enough to aid present day instruction?    The junior high school coverage of complex numbers gives a context for rotations, translations and reflections of points in the plane. 

The only reason for the study of the following topics is calculus or preparation for it. 

About Euclidean-Geometry  

This topic at full strength  may be be too complicated for students.  Here is a simple route that depends only on the forward use of implication rules if A then B, all presented in a manner that provides a base for the discussion of similarity, right triangle trig and the site development of complex numbers.  The review of triangle construction methods may be useful to  late primary school or early secondary school instruction. 

About Lines,  slopes & equations

  • Numerical Introduction (skip if it is not to your liking)
  • Slopes and Lines Deriving Equations
  • Perpendicular Lines. Understand why the slopes of perpendicular pairs of slanted lines (lines not vertical not horizontal) are negative multiplicative inverses (negative reciprocals) of each other. 
  • Three Equations Forms -  point-slope, slope intercept and two-point forms.  (Symmetric form not covered). 
  • From Equations to Lines Numerically - Here is the algebraic viewpoint of equations for straight lines.
  • Intersection point of lines- Two lines are parallel or they intersect. Learn how to recognize parallel lines from equations for lines, and learn solve systems of linear equations to find intersection points. 
  • Exercises - Five Questions to Test  knowledge.  

There is a different, less detailed, viewpoint in site area Maps, Plans,  Similarity & Trig

About Polynomials and Quadratics.

Discussion of fractions with units provides an contextful alternative to the algebraic manipulations of monomials - their addition, products and ratios.  The site introduction of multiplication, addition, subtraction and long division of polynomials provide a quick mechanical mastery of these operation in courses where learning to do is more important or may come before theory.  The path here develops algebraic skills without overwhelming students with technical justifications. The site coverage of quadratics is aim at students entering calculus, students for whom mastery of technical details, those here, will be beneficial.  

About Functions 
Forwards & Backwards

The set and rule-views of functions and relations are cleverly combined here not to emphasize the set theory development of mathematics, but to provide an operational command of function concepts needed in calculus. Explanations and notation should aid comprehension and skill mastery, and not be overwhelming. 

 

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Parents: Help your Child/Teen Learn covers  Speaking Skills, Reading & Writing Preparing for Science Having Patience, etc

Math How-TOs
1. Arithmetic   2. Algebra   3.  More Algebra  4.  Geometry 5 More Geometry 6.  Calculus
>> densely written 
>> use as skill checklists

Online Volumes (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

Site Areas and SubAreas
 
2     Fractions  
3.      Fractions  with Units  
3.    Solving Linear Equations  - making alg easier
4.  Formulas forwards & Backwards - a  theme
5.     Proportionality, Back- & For-wards
6.       Euclidean-Geometry  (lean intro)
7.      Logic - Math Free, good for work & studies
8.    Slopes and Lines
9.  Why Study Slopes - Advanced Motivation 
10.    Quadratics and  Polynomials
11. Application of Factored Polynomials
12    Functions - Forwards & Backwards
13        Number Theory, Richly
14.     Exponents, Radicals & logs.  
15    Calculus - Examples & Blah, Blah, Blah 
16.   Real  Analysis 
17.  Electric Circuits Etc (So So)
18. Maps, Plans,  Similarity & Trig, (alt view)
19.    Complex numbers  - a visual approach

20.       Logic with Symbols (and truth tables)

21.     Logic & Consistent Story Telling
22. Even More Logic

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Singing for my supper:  For  (i) an online or offline mathematics  instruction or (ii) a technical writer,  email site author Alan Selby.

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The site author offers live skill development lessons online