Saturday, March 21, 2015

Number Line Gallery Walk

My students did poorly last year on number line questions because I did not emphasize the precision and attention to detail necessary to accurately depict a set of numbers on a number line. I was determined this year to find a way to teach this topic more effectively.

This year I started out by showing the students examples of number lines:

After studying these examples, we discussed what elements these numbers lines had and from this discussion we created a number line checklist that students would use to make sure that their numbers lines contained all the elements needed for accurate numbers lines.

Here are some examples of student created number lines. There are some small errors in these number lines, which I did not correct as I circulated during class. During the Number Line Gallery Walk, I wanted students to have the chance to go through the number line check list for each number line to find any errors.

1) Draw a horizontal number line to represent the set of numbers:  Even numbers between 30 and 45.

2) Draw a vertical number line to represent the set of numbers:  Whole numbers greater than 20 but less than 27.

3) Draw a vertical number line to represent the set of numbers: Decimals between 9.4 to 10.5 with an interval of 0.1 between each pair of decimal.

4) Draw a horizontal number line to represent the set of numbers: Mixed number from 6 to 7, with an interval of 1/5 between each pair of mixed numbers.


5) Draw a vertical number line to represent the set of numbers: Mixed numbers between 5 and 7, with an interval of 1/3 between each pair of mixed numbers.

After the students completed the number lines, groups displayed their number lines around the classroom and then using their number line check list did a gallery walk and evaluated each number line in small groups. There was great discussion in the groups about whether or not a number line met all the criteria for an accurate number line. 

I prepared a PowerPoint presentation for the next day by taking photographs of the number lines so they could be displayed in front for all to see and this was tremendously helpful to facilitate discussion. First, I asked the group who made the number line to decide whether their number line was accurate, and then I opened it up for class discussion.

The construction of number lines on large graph paper, small group work, the gallery walk including peer evaluation and error analysis and finally a class discussion with number lines projected for all to see, helped turn a somewhat dry and tedious topic into a very productive and engaging lesson for my students.

These see through colored dots that I found at Staples were great because it allowed students to add dots to their number lines and still see the tick marks below. The difference between tick marks and dots, has been difficult for some of my students and I think the stickers dots helped them make the distinction between tick marks and dots and why all numbers on the number line need tick marks and only some numbers get dots.

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