| Students Need to Have Basic Mental Math Ability | | | | like 4x/4 = 2/4. This is partly the problem for some |
| | | | | math teachers who have always taught students to |
| Frank Ho, Amanda Ho | | | | physically and visually carry out the computation and |
| Ho Math and Chess Learning Centre | | | | do not encourage mental math computation. It is a |
| Canada certified math teacher | | | | good idea to promote mental math computation |
| Vancouver, BC, Canada | | | | whenever it is possible. |
| | | | | When going to high school, students will continue to |
| | | | | lack behind in doing trinomial factoring since they will |
| In our over fifteen years of teaching math | | | | not remember the formulas of the square of x + y |
| experience, we have witnessed how important it is | | | | or what are factors of x squared minus y squared |
| for students to have basic mental math ability. What | | | | etc. Because of these reasons, they will have |
| is basic mental math ability? We are not talking about | | | | difficulty in seeing how to rationalize 1 /(square root |
| how fast a student can do 15 times 16 in a few | | | | of 3 plus 2). |
| seconds or if a students can remember the ratio of | | | | They seem to have difficulty in doing completing the |
| a circumference to its diameter to 10th decimal place. | | | | square method for coming up with a standard form |
| We are referring to a condition that if students do | | | | of a parabola. |
| not possess this kind of math mental ability then | | | | When working on rational expression, students have |
| they will not have adequate “number sense” | | | | difficulties in finding the GCF of x square + 2x + 1 |
| and thus it hampers them from developing good | | | | and (x + 1) square because they do not know that |
| math ability. One area seems to stand out to strike a | | | | (x square + 2x + 1) = (x + 1) squared. |
| major difference is student’s factoring ability | | | | When working on square root and cubed roots, |
| (reverse of time table). We would like to give some | | | | students have trouble to see the root of 4 is 2 and |
| examples to illustrate how important it is for students | | | | the root of 27 is 3 and have some difficulties in |
| to develop the mental math ability in factoring. | | | | coming up answers for some numbers because they |
| To reduce 9/15, students are not able to quickly see | | | | could not come up with perfect square numbers and |
| its greatest common factor is 3 then they will have | | | | cubed numbers quickly. |
| trouble to simplify its fraction. It is very important for | | | | For a bit more complicated factoring problems, then |
| students to know how to simplify a fraction. For | | | | students basically are lost. For example, to factor x |
| example, it will be difficult for students to do this | | | | cubed + 3 x squared – 16 x – 48, students |
| fraction if they do not know how to simplify 3/5 | | | | have no clue in how to factor this expression if they |
| times 25/9 times 18/50. All these problems require | | | | do not have mental math ability since the coefficient |
| students to have very basic factoring ability and if | | | | gives clues but they can not see the relationship |
| students have not mastered times table this could be | | | | between numbers. |
| the time they get frustrated with math. | | | | Many times, students can not prove trigonometry |
| Factoring not only affects simplifying fractions, it also | | | | identities because they do not know which identity |
| affects equation solving. For example, 4x = 2 is a | | | | formulas to use. Without any idea of which identity |
| very simple equation and yet so many students are | | | | formula to use, they do not have any instinct on |
| not able to solving it without visually doing a division | | | | how to prove an equation. |