Comments for SL2RL-Math247 http://www.mathcasts.org/janita Second Life & Real Life Mathematics Thu, 01 Apr 2010 00:12:02 +0000 hourly 1 http://wordpress.org/?v=3.2.1 Comment on Race Car Activity – Exploring Slope and Intercepts in the Real World by math applets http://www.mathcasts.org/janita/?p=29&cpage=1#comment-465 math applets Thu, 01 Apr 2010 00:12:02 +0000 http://www.mathcasts.org/janita/?p=29#comment-465 [...] unique or otherwise useful. Here is a great source for math games, puzzles and ideas for courseRace Car Activity Exploring Slope and Intercepts in the ...Filed under: ICT, applets, education, math Tags: geogebra admin @ 10:23 pm. Click and drag the [...] [...] unique or otherwise useful. Here is a great source for math games, puzzles and ideas for courseRace Car Activity Exploring Slope and Intercepts in the …Filed under: ICT, applets, education, math Tags: geogebra admin @ 10:23 pm. Click and drag the [...]

]]> Comment on Baddie of the Month – Teaching complex numbers with the quadratic formula by quadratic function http://www.mathcasts.org/janita/?p=157&cpage=1#comment-463 quadratic function Fri, 19 Mar 2010 07:26:29 +0000 http://www.mathcasts.org/janita/?p=157#comment-463 [...] is a quadratic function of n. Therefore, the total running time is directly proportional to n2. ...Baddie of the Month Teaching complex numbers with the ...Conclusion: Do NOT mention complex numbers at all when teaching the quadratic formula. ... quadratic [...] [...] is a quadratic function of n. Therefore, the total running time is directly proportional to n2. …Baddie of the Month Teaching complex numbers with the …Conclusion: Do NOT mention complex numbers at all when teaching the quadratic formula. … quadratic [...]

]]> Comment on Race Car Activity – Exploring Slope and Intercepts in the Real World by dissertation writing service http://www.mathcasts.org/janita/?p=29&cpage=1#comment-462 dissertation writing service Tue, 16 Mar 2010 15:04:54 +0000 http://www.mathcasts.org/janita/?p=29#comment-462 great car :) thanks great car :) thanks

]]> Comment on Baddie of the Month: October 2009 by Essay Writing Service http://www.mathcasts.org/janita/?p=213&cpage=1#comment-452 Essay Writing Service Mon, 11 Jan 2010 15:57:29 +0000 http://www.mathcasts.org/janita/?p=213#comment-452 Thanks for this formula. Very interesting post. Thanks for this formula. Very interesting post.

]]> Comment on Thinking questions for rates by The Math Maker http://www.mathcasts.org/janita/?p=194&cpage=1#comment-65 The Math Maker Mon, 18 May 2009 19:43:43 +0000 http://www.mathcasts.org/janita/?p=194#comment-65 I like the last two examples which show the relationship between distance, time and speed in different ways. A rather strange thing is that I found that students struggle more with the third form than the second form and yet neither is really more complicated than the other. Perhaps it's the way students are taught the formula, s=ut (s=distance,u=speed), and then have difficulty recognizing its other forms (apart from algebraic difficulty of changing the subject of the equation). Thanks again for the interesting post! I like the last two examples which show the relationship between distance, time and speed in different ways. A rather strange thing is that I found that students struggle more with the third form than the second form and yet neither is really more complicated than the other. Perhaps it’s the way students are taught the formula, s=ut (s=distance,u=speed), and then have difficulty recognizing its other forms (apart from algebraic difficulty of changing the subject of the equation). Thanks again for the interesting post!

]]> Comment on Goodie for April 2009 by The Math Maker http://www.mathcasts.org/janita/?p=186&cpage=1#comment-56 The Math Maker Wed, 29 Apr 2009 22:31:56 +0000 http://www.mathcasts.org/janita/?p=186#comment-56 When I read this, you reminded me of a little problem I used to use with Physics students; indirectly related, the harmonic mean (although you can have a weighted harmonic mean). The simplest version; a person travels from A to B at 20 mi/h and immediately returns at 30 mi/h; what is the average speed for the total journey assuming that the time to turn around is negligible? You guessed it, just about every time I got the answer 25 mi/h! Thanks for the great posts. When I read this, you reminded me of a little problem I used to use with Physics students; indirectly related, the harmonic mean (although you can have a weighted harmonic mean). The simplest version; a person travels from A to B at 20 mi/h and immediately returns at 30 mi/h; what is the average speed for the total journey assuming that the time to turn around is negligible? You guessed it, just about every time I got the answer 25 mi/h! Thanks for the great posts.

]]> Comment on Goodie for April 2009 by Dani http://www.mathcasts.org/janita/?p=186&cpage=1#comment-55 Dani Mon, 27 Apr 2009 11:58:05 +0000 http://www.mathcasts.org/janita/?p=186#comment-55 This is very interesting. Would it be possible to build a simulation for this problem? the x% will be the variable. while the students could also change the other "variable" as sliders and I have a feeling it could be also represented graphically. What is so nice about GeoGebra that it provides such a strong visual connection between pictures, numbers, graphs, spreadsheets... Also the best thing is to teach students to DO the simulations because then THEY are doing the Math themselves. This is very interesting. Would it be possible to build a simulation for this problem? the x% will be the variable. while the students could also change the other “variable” as sliders and I have a feeling it could be also represented graphically. What is so nice about GeoGebra that it provides such a strong visual connection between pictures, numbers, graphs, spreadsheets… Also the best thing is to teach students to DO the simulations because then THEY are doing the Math themselves.

]]> Comment on Baddie of the Month – Factoring a Quadratic with a≠1 by admin http://www.mathcasts.org/janita/?p=43&cpage=1#comment-54 admin Mon, 27 Apr 2009 06:20:19 +0000 http://www.mathcasts.org/janita/?p=43#comment-54 If only the problem was "Factor 13x^2 + 14x + 1". My sample problems are: "Using either Lagrange's or Newton's interpolation method, find the polynomial of smallest order that passes through the points (-1,0), (0,1) and (1,28). Graph this function finding all intercepts and extreme values and show that it goes through these points.". These kids don't have time to mess around with factoring - which NO ONE ever remembers or uses after Algebra 1 or with completing the square. The quadratic formula is tedious? No way! It is an easy to remember formula that works every time. If only the problem was “Factor 13x^2 + 14x + 1″. My sample problems are: “Using either Lagrange’s or Newton’s interpolation method, find the polynomial of smallest order that passes through the points (-1,0), (0,1) and (1,28). Graph this function finding all intercepts and extreme values and show that it goes through these points.”. These kids don’t have time to mess around with factoring – which NO ONE ever remembers or uses after Algebra 1 or with completing the square. The quadratic formula is tedious? No way! It is an easy to remember formula that works every time.

]]> Comment on Baddie of the Month – Factoring a Quadratic with a≠1 by Jonathan http://www.mathcasts.org/janita/?p=43&cpage=1#comment-52 Jonathan Mon, 13 Apr 2009 00:02:13 +0000 http://www.mathcasts.org/janita/?p=43#comment-52 Formula for 13x^2 + 14x + 1 ? No. Tsk tsk. If it takes less than a minute to check if an expression is factorable, why not? Before running the tedious formula. Special cases? I have none. One method for all, allows to check if an expression is factorable before doing the work. Try this: <a href='http://jd2718.wordpress.com/2007/08/19/teaching-factoring-should-we/' rel="nofollow">Teaching Factoring - Should we?</a> and I'd be happy to point you towards a discussion of trinomial factoring by breaking the middle. Formula for 13x^2 + 14x + 1 ? No. Tsk tsk.

If it takes less than a minute to check if an expression is factorable, why not? Before running the tedious formula.

Special cases? I have none. One method for all, allows to check if an expression is factorable before doing the work.

Try this: Teaching Factoring – Should we? and I’d be happy to point you towards a discussion of trinomial factoring by breaking the middle.

]]> Comment on Baddie of the Month – Teaching “completing the square” for quadratics by Jonathan http://www.mathcasts.org/janita/?p=104&cpage=1#comment-51 Jonathan Sun, 12 Apr 2009 23:42:04 +0000 http://www.mathcasts.org/janita/?p=104#comment-51 There are only two reasons to teach completing the square: 1) so that students can observe the derivation of the quadratic formula, and have an idea of what is going on; and 2) for manipulating equations and expressions at an algebra II or precalc level (ex to find center and radius for x^2 + 6x + y^2 - 10x = 1 or to factor x^4 + 4 ) At the Algebra I level, the first reason makes sense - I wouldn't want a kid to take a formula on faith - but not for graphing, when there are perfectly powerful tools available that are far less complex. There are only two reasons to teach completing the square:
1) so that students can observe the derivation of the quadratic formula, and have an idea of what is going on; and
2) for manipulating equations and expressions at an algebra II or precalc level (ex to find center and radius for x^2 + 6x + y^2 – 10x = 1 or to factor x^4 + 4 )

At the Algebra I level, the first reason makes sense – I wouldn’t want a kid to take a formula on faith – but not for graphing, when there are perfectly powerful tools available that are far less complex.

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