Thursday, November 5, 2009

A New Math Word

My husband's seventh grade class has come up with a new math term! In science they have learned that the prefix "eu" means true. So eubacteria, as opposed to archeabacteria, means true bacteria.  And eukariotic means true nucleus. 

In math, they are learning about variables. Now the definition of variable is "a value that can change". In the the equation y=2x + 5, the variables are x and y. And their values can change.

But sometimes variables or letters are used just to hold a place and the value is pre-determined. An example of this is in the equation 2x +3 = 7. In this case x=2 and the variable is holding the place of the 2.

So the new math word? Here it is: EUVARIABLE!!! It means a true variable and not just a place holder.

Congratulations to my husband and his seventh graders! Good thinking!

Integer Hi-Lo

I came up with a new game and my last period eighth grade group named it! I needed to review multiplying integers with them.

I started by dividing the students into groups of two, three, or four and giving them a deck of cards. I wrote on the board that black cards were positive and red cards were negative. I told them it was that way with the phrases "in the black" and "in the red."

The dealer hands out all the cards to the players. The cards are placed face-down and the players don't look at them. Whoever has been designated to go first puts out one card. If it is black, they are looking for the highest product; if it is red, they are looking for the lowest product. Then the first player lays out another card and announces the product of his two cards. The next player puts out two cards and announces their product until all players have done this. They then decide who has the high or low depending on what they are looking for based on the first card out. The winner takes all the cards and puts them under their deck face-down.

Players are trying to end up with all the cards. If there are more than two people playing, I cut the game off when one person has no cards and the person with the most is declared the winner. If the class ends, the person with the most cards wins.

This is a good game not only for multiplying integers, but also comparing integers. Sometimes students struggle with the concept that -50 is less than -1, and this game helps them review magnitude.