alligator method

The alligator eats the bigger number is the common approach for student to use inequality symbols (< > < > ). I find that students remember the sentence but many do not retain the concept or use the symbols correctly, even in high school. This post presents an alternative approach.

The reason, I believe, is that we introduce additional extraneous information: the act of eating, the mouth which is supposed to translate into a symbol, the alligator itself. For a student with processing or working memory challenges this additional information can be counter productive.

Dot Method

I use the dot method. By way of example here is the dot method. I show the symbols and highlight the end points to show one side has 2 dots and the other, 1.

Then I show 2 numbers such as 3 and 5 and ask “which is bigger?” In most cases the student indicates 5. I explain that because 5 is bigger it gets the 2 dots and then the 3 gets the 1 dot.

I then draw the lines to reveal the symbol. This method explicitly highlights the features of the symbol so the symbol can be more effectively interpreted.

Concept of Inequalities

That is the presentation of the symbol. To address the concept of more, especially for students more severely impacted by a disability, I use the following approach. I ask the parent for a favorite food item of the student, e.g. chicken nuggets. I then show two choices (pretend the nuggets look exactly the same) and prompt the student to make a selection. This brings in their intuitive understanding of more.

concept of more chicken nuggets just plates

I think use the term “more than” by pointing to the plate with more and explain “this plate has more than this other plate.” I go on to use the quantities.

concept of more chicken nuggets more than words

Finally, I introduce the symbol to represent this situation.

concept of more chicken nuggets more than symbol

Below is the example my 3rd grade son used to explain less than to a classmate with autism. This method worked for the classmate!

I have found that many students I have taught, including in college, struggle with the inequality symbols. Typically, they cannot remember which symbol is less than or greater than despite various efforts such as the “alligator eats the bigger number” method.

I’ve found traction by using the dot method. It is like a light bulb clicking on for many of the students. I believe the reason is works is that it explicitly addresses the shape. Here’s the approach.

Show them an inequality statement
Tell them to think of the end points as dots.
Draw the dots.
Ask, “which number is bigger?”
Point out that the bigger number has more dots.

Show them two numbers, say 4 and 6.
Ask which is bigger?
Draw two dots for the 6 because the bigger number gets two dots.
Draw one for the 4.
Finally, draw the symbol.

Tag: alligator method

More Than: Concept and Symbol

The alligator eats the bigger number is the common approach for student to use inequality symbols (< > < > ). I find that students remember the sentence but many do not retain the concept or use the symbols correctly, even in high school. This post presents an alternative approach.