"An inequality is similar to an equation. There are two expressions separated by a symbol that indicates how one expression is related to the other. In an equation such as 7x = 49, the = sign indicates that the expressions are equivalent. In an inequality, such as 7x > 49, the > sign indicates that the left side is larger than the right side.
To solve the inequality 7x > 49, we follow the same rules that we did for equations. In this case, divide both sides by 7 so that x > 7. This means that x is a value and it is always larger than 7, and never equal to or less than 7.
The "less than" symbol (<) may also be seen in inequalities. " To remember this, we have the "Alligator rule". The alligator wants to eat the bigger number, therefore his mouth is open to the 10 and not the 5: 5
10If the number on the left were smaller, the alligator head would face the other way, as in this picture.
3
2Another symbol is the "not equal" sign
, when you see this symbol you know that either it is greater than (>) or less than (<) but it is not equal. For instance if you were to have a 
b, so it would have to be either a (<) b or a (>) b.
I completely forgot about how you can explain inequalities with the "Alligator rule". This would explain inequalities in a much easier, understandable, and fun way for kids.
ReplyDeleteThat is exactly what I was thinking. I think you can show young students the "Alligator rule" to make the less than or greater than symbols easy to understand. Even sometimes I have to think about that rule! HAH.
ReplyDeleteThere is something to be careful about here, though. If a student only learns < and > in the context of which number is bigger, then they have a lot of trouble later on with reading or understanding an expression with no numbers, like x < y. Also, what are you going to do in the case where one number is actually a larger font, but smaller in magnitude? (imagine a small-font 5 next to a large-font 3)
ReplyDeleteIt also presents a problem with negative numbers, since the ones that seem larger, are actually lesser. For example, -5 > -10 (even though intuitively, 10 is greater than 5).
I love gator math! One of the things that I will always remember from second grade is how my teacher taught this to me. She used a puppet and showed what it wanted to "eat" (the bigger number). But, Mrs. Andersen is right -- the only way I learned was "bigger", it confused me later in life.
ReplyDelete