Common Mistakes in Teaching Elementary Math-And How to Avoid Them : And How to Avoid Them (Paperback)

Meet the Author Preface Chapter 1 Counting Counting Shouldn't Start at 0 What Are Tally Marks for? It May Not Be Fast?The Purpose of Skip-Counting Our Number System Is Base-Ten, Not Base-Twelve Chapter 2 Number Properties A Red Marble Isn't More Than a Blue One Playing Cards and Dice Aren't Ideal Things to Make Multidigit Numbers With It's Odd Not to Consider 0 as Even 14 and 37 Don't Belong in the Same List Chapter 3 Addition 4 + 4 Isn't Simply 8 Bars Put Together Make Pictorial Representations More Than a "Literal" Translation Don’t Hop From Square One You Can't Add Apples and Oranges Together Chapter 4 Subtraction Don't Make the Kittens Disappear Don't Ever Say "Subtract the Smaller Number From the Larger One" "Neither a Borrower nor a Lender Be"?Why We Shouldn't Borrow Can We Subtract a Larger Number From a Smaller One? 10 + 5 ? 8 = 15 ? 8: No Way to Make It Simpler? Chapter 5 Multiplication The Formidable 169-Cell Multiplication Table "You Must Put a Zero in the Ones Place" Can You Move Over One Place Value? Line Multiplication: Why It Won't Work Chapter 6 Division The Bigger Number Doesn't Always Go Inside What's 0 ¸ 0? Division Isn't Always Repeated Subtraction "Dad, Mom, Sister, Brother, Rover": Where Is Dad? Divide Doesn't Always Yield a Smaller Number Chapter 7 The Order of Operations Aunt Sally Is Evil ? The Order of Operations The Order "M/D Before A/S" Isn't Haphazard Are Negative and Subtract Really Different? Chapter 8 Algebra An Equal Sign Means Equal What Does Adding Up Numbers Landed Have to Do With Finding Factors? Timelines Aren't Good Candidates for Teaching Negative Numbers The Worst Example in Teaching Exponents Chapter 9 Geometry: Bits and Pieces Don't Count the Diagonals on a Grid "All 3-D Shapes Have an Extra Third Dimension of Height" Don't Use "Vertical" to Find the Horizontal Value The Two Sides of a Symmetrical Figure Aren't Exactly the Same Don't Use Tiles to Figure Out the Perimeter Chapter 10 Geometry: Common Geometric Figures Length Doesn't Necessarily Mean Longer A Rectangle's Orientation Doesn't Matter Either "A Rectangle Has Two Longer Sides and Two Shorter Sides" What's Wrong With Saying "Triangles, Rectangles, Squares, and Hexagons"? Base Doesn't Necessarily Mean "Side at Bottom" Three Sides Don't Necessarily Make a Triangle How Many Sides Does a Circle Have? Chapter 11 Time-Telling "A Quarter in Time Means 15" Does 1 on Analog Clocks Mean 5 Minutes? "Why Does the Time on My Analog Clock Look Weird?" Which Hand Pointing to 12 Makes 12 O'clock? Why We Shouldn't Jump Around Between 8:00 and 9:00 Chapter 12 Fractions A Condition for Using Fractions: Equivalent Parts "Bottom Number" and "Top Number" Aren't Nearly Sufficient for Defining Denominators and Numerators What Does 1/2x Mean? A Fraction Doesn't Address "How Many" Denominators Should Be Substantially Different for Easy Comparison Percentage Shouldn't Be Juxtaposed With Fractions and Decimals Chapter 13 Decimals Changing the Value Scheme of Base-10 Blocks Not a Good Idea When Is It Appropriate to Read a Decimal as a Fraction? 25.0 and 25 Aren't Exactly the Same Keep a Few More Decimal Places When Rounding at Intermediate Steps Chapter 14 Simple Statistics and Graphs Were the Children in Your Class Born, on Average, on the 12.8th? "The Mean Is the Average" Where in the World Does the Mode Ever Get Used? Do All Your Children Have an Equal Chance of Winning? Use Different Types of Data for a Beginning Lesson on Graphs Chapter 15 Measurement Why Do We Need Nonstandard Measurement? What Is Standard Measurement? What Are Centimeters Used to Measure? Leave Out Units of Measure at Intermediate Steps How Do You Say the Word for "1000 Meters"? Fractions Don't Belong With Metric Measurements Chapter 16 Computational Estimation Is Computational Estimation an Educated Guess? Are All Estimates Good Ones? How Practical Is an Estimate If It Takes Four Minutes? Be Extremely Careful When Rounding Single-Digit Numbers There Is Often More Than One Way to Round a Number Chapter 17 Odds and Ends Appendix: Suggestions for Using Common Mistakes in Teaching Elementary Math with Study Groups