Math Monday: Play Common Denominator War

Disclosure / Disclaimer: I received this info, free of charge,from Education.com, for blog posting purposes on this blog. No compensation, monetary or in kind, has been received or implied for this post. Nor was I told how to post about it,  all opinions are my own.



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This month just seems to be filled with MATH (ie Pi Day coming up NEXT week, so I thought, why not have a Math Monday feature this month?

Thanks to our friends over at Education.com (a resource I use a WHOLE lot in homeschooling Miss Grace for quizzes and extra worksheets), I have a great way to get older elementary kids, who may be struggling with fractions some help!

common denominator war

If you have a child who is balking at fractions, a game of Common Denominator War can help! Finding the least common denominator (LCD) of two fractions is one of the basic skills needed to work with fractions. You can find the common denominator of two fractions by finding the smallest number that is a multiple of both of them (lowest common multiple). This activity will give children plenty of practice in figuring out the lowest common multiple of two numbers.

What You Need:

  • Index cards
  • Permanent marker
What You Do:
  1. Write numbers on at least 20 index cards, making sure that most of the numbers are not prime. For example, you might choose numbers such as 8 (which has the factors 2 and 4) or 9 (which has 3 as a factor) more often than 7 or 11, which are both prime. Most of the numbers should be between 1 and 20, with a few larger ones that have a lot of factors (e.g., 20, 24, 30).
  2. Divide the pile of index cards in half into two smaller piles, and give each player one of these smaller piles.
  3. Both players call out “1, 2, 3…war!” and simultaneously turn over the top card in their piles and place it between them.
  4. The goal: as quickly as each player can, calculate the lowest common multiple of the numbers on the two cards, and call it out.
  5. The first player to call out the correct lowest common multiple wins the round and gets to add both of the cards to the bottom of her pile. Repeat Steps 3 and 4 for the next round.
  6. The game ends when one player runs out of cards. The other player is the winner.

About Education.com

From school teachers and tutors to home schoolers and parents, engaged adults are the key to unlocking each child's potential and drive to learn. We empower all kinds of educators to teach kids by providing the best educational resources in any form or device to be used at home, at school, and everywhere in-between.There is no such thing as "one size fits all" in education; each educator and child has unique challenges and goals. We celebrate the diversity of our users by offering differentiated resources that can meet a wide range of educational needs - and raise kids' confidence in learning, in fact we provide learning resources in over 20 countries and six continents. We offer Guided Lessons, Learning Resources and Teaching Tools for teachers and homeschool educators alike, for grades pre-K through 5th grade.

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