Tuesday, July 13, 2010
Continue the Excitement!
So, you have caught your students’ attention with the 11 trick for double digit numbers and maybe showed them how to work with larger whole numbers times 11 (multiply by 11 expanded) as shown in Fantastic Math tricks. Now what? If you know that at some point in time during the school year you will need to simplify fractions and you will work with percents, I would suggest you build the skill of working with 25. I convince my students that they can do division with a double-digit divisor in their heads!! How? The double-digit divisor is 25. First, I will ask them how many quarters are in $1.25, in $3.75, in $8.25 and in $10.00. I tell them to take the dollar amount times 4 and then add in the number of quarters needed for the cents. Yes, I do make sure I am working with a multiple of 25. Then I will relate this to 125 ÷ 25. I tell my students the 25 is a quarter and the 125 is $1.25, so how many quarters are in $1.25? Relate math to money and students will catch quickly! In no time at all your students will be doing 1175 ÷ 25 (answer is 47 as there are 44 quarters in $11 and then you need three more for the 75 cents) and 2050 ÷ 25 (answer is 82 as there are 80 quarters in $20 and then you need two more for the 50 cents). What you have done is empowered your students – they are in control of the numbers as opposed to the numbers controlling them. By mastering the skill of working with 25, your students will find it easier to simplify fractions like 275/1000.
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Jeannie~
ReplyDeleteI agree with your post about students being able to compute math problems quicker mentally when a relation to money is taught. After reading your math tip from last week, I must of had math on the brain and I came across a voice thread that shows a trick with 2 digit multiplication. Here is the link as you may be interested. P.S. There is one error and I bet you spot it right away!
http://voicethread.com/#q+math.b26603.i147344
Kacey,
ReplyDeleteI watched the voicethread - thank you for the link. As an educator what concerns me more than the error is that why the trick works is never discussed. I love math and want to "hook" my students, but at some point in time we need to explain why the trick works. Better yet, I want them to demand that I explain why it works!
Coming from a middle school prospective, I totally agree with you that tricks are a great way to hook students in and yet we need to have them strive to find out why the trick works! It's too easy for them to get caught up in "Hey, I don't have to think anymore, I'll just use the trick" and then then they walk away with little understanding.
ReplyDeleteThanks for the link to Fantastic Math tricks... always searching for them too!