{"id":309,"date":"2011-01-16T10:30:59","date_gmt":"2011-01-16T02:30:59","guid":{"rendered":"http:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/?p=309"},"modified":"2024-02-16T21:14:00","modified_gmt":"2024-02-16T13:14:00","slug":"another-way-to-teach-fraction-division","status":"publish","type":"post","link":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/2011\/01\/another-way-to-teach-fraction-division\/","title":{"rendered":"Another Way To Teach Fraction Division"},"content":{"rendered":"<p>The classic way to teach fraction division is like this. To work out, say,<\/p>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=7&amp;c=12&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%f7&amp;b=2&amp;c=9&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<p>we &#8216;turn the second fraction upside-down&#8217;, to get<\/p>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=7&amp;c=12&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=x&amp;b=9&amp;c=2&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<p>and then the division question becomes a multiplication question.<\/p>\n<p><!--more-->I&#8217;ve been watching my son do a whole bunch of fractions questions lately, and a couple of thoughts crossed my mind. First of all, this method will confuse some students. Secondly, there&#8217;s another way to do fraction division.<\/p>\n<p>With fraction arithmetic, we give the students procedures for working out various sums. For addition and subtraction, &#8216;put the fractions over a common denominator&#8217;. For multiplication, &#8216;multiply the top and bottom&#8217;. For division, &#8216;convert it to a multiplication problem&#8217;. Ideally, kids would know these methods and the reasons why they work. However, faced with the limited time available in a lower school classroom (and the limited attention span of a typical lower school pupil), I guess a teacher can consider him\/herself lucky if an average student just learns the procedures.<\/p>\n<p>In any case, it&#8217;s easier to test if a student can solve fractions problems than to test if they understand fractions.<\/p>\n<p>If we teach<\/p>\n<ul>\n<li>For addition and subtraction, put the fractions over a common denominator and combine<\/li>\n<li>For multiplication, multiply top and bottom<\/li>\n<li>For division, turn the second fraction upside down, then multiply<\/li>\n<\/ul>\n<p>then<\/p>\n<ul>\n<li>we are teaching three procedures for four operations<\/li>\n<li>the procedure for division is hard to justify without appealing to a deeper understanding of fractions than most kids will have obtained.<\/li>\n<\/ul>\n<p>At least the idea of putting things over a common denominator can make sense without too much trouble, as well the way you need to combine the fractions afterwards. For example<\/p>\n<ul>\n<li>If you have 12 oranges, and add 5 oranges, how many oranges do you have? 17 oranges.<\/li>\n<li>If you have 12 fifteenths, and add 5 fifteenths, how many fifteenths do you have? 17 fifteenths. So,<\/li>\n<\/ul>\n<div>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=12&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%2b&amp;b=5&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%3d&amp;b=17&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<\/div>\n<p>Subtraction is similar &#8211;<\/p>\n<ul>\n<li>If you have 12 apples, and take away 5 apples, how many apples do you have? 7 apples.<\/li>\n<li>If you have 12 fifteenths, and take away 5 fifteenths, how many fifteenths do you have? 7 fifteenths. So,<\/li>\n<\/ul>\n<div>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=12&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=-&amp;b=5&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%3d&amp;b=7&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<\/div>\n<p>Is there any reason not to use the same approach for division?<\/p>\n<ul>\n<li>If you have 12 pizzas, and share them into groups of 5 pizzas, how many pizzas per group? The answer is 12 divided by 5.<\/li>\n<li>If you have 12 fifteenths, and share them into groups of 5 fifteenths, how many fifteenths per group? The answer is 12 divided by 5<\/li>\n<\/ul>\n<div>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=12&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%f7&amp;b=5&amp;c=15&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%3d&amp;b=12&amp;c=5&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<\/div>\n<p>You can easily check that the standard method gives the same answer.<\/p>\n<p>In full detail, this method for dividing fractions looks like this :<\/p>\n<ul>\n<li>Convert both fractions so that they are over a common denominator.<\/li>\n<li>Divide the numerators of the two fractions.<\/li>\n<\/ul>\n<p>I&#8217;ll illustrate this with the original example I gave above.<\/p>\n<p style=\"text-align: center;\"><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?b=7&amp;c=12&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%f7&amp;b=2&amp;c=9&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%3d&amp;b=21&amp;c=36&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%f7&amp;b=8&amp;c=36&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><img decoding=\"async\" style=\"margin: 0px; border: 0px; padding: 0px;\" src=\"http:\/\/www.dr-mikes-math-games-for-kids.com\/images\/createFraction.php?a=%3d&amp;b=21&amp;c=8&amp;rd=7&amp;gr=49&amp;bl=213&amp;font=24\" alt=\"\" \/><\/p>\n<p>If this were the standard method kids were taught to divide fractions, we would teach<\/p>\n<ul>\n<li>For addition, subtraction and division, put the fractions over a common denominator and combine<\/li>\n<li>For multiplication, multiply top and bottom<\/li>\n<\/ul>\n<p>then it&#8217;s possible that fraction arithmetic would be easier to grasp all round.<\/p>\n<p>Or it might not. For every student who struggles with the &#8216;standard method&#8217; of fraction division, there will probably be five who are greatly relieved that it doesn&#8217;t involve common denominators. Nor would I particularly recommend teaching <em>both<\/em> methods to an entire class and letting them pick for themselves. Although it&#8217;s worth knowing that many mathematical problems will bow to several different methods, there&#8217;s also the danger that different methods, shakily memorized, will combine confusedly in the pupil&#8217;s mind and completely mess up their ability to work with fractions.<\/p>\n<p>Instead, I&#8217;d recommend<\/p>\n<ul>\n<li>Keep this method in mind for the occasional student who just doesn&#8217;t &#8220;get&#8221; the standard method for fraction division, but has no trouble with common denominators.<\/li>\n<li>Also, show it to those students bright and interested enough that they will benefit from being exposed to new approaches to familiar problems.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>The classic way to teach fraction division is like this. To work out, say, we &#8216;turn the second fraction upside-down&#8217;, to get and then the division question becomes a multiplication question.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[8,196,195,51,197],"_links":{"self":[{"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/posts\/309"}],"collection":[{"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/comments?post=309"}],"version-history":[{"count":1,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/posts\/309\/revisions"}],"predecessor-version":[{"id":1401,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/posts\/309\/revisions\/1401"}],"wp:attachment":[{"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/media?parent=309"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/categories?post=309"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dr-mikes-math-games-for-kids.com\/blog\/wp-json\/wp\/v2\/tags?post=309"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}