Friday, September 5, 2014

Using the Number line to Round

This was our first week of working hard in 3rd grade. I was so proud of my 3rd graders. We hit the ground running in math this week. Our first unit is learning how to round numbers to the nearest 10 and 100.

I started the unit off with a pre-test to see what we remember. This quick test is mainly to see if we could remember from 2nd grade how to skip count to 1,000 by 10’s and 100’s. I was pleasantly pleased with my students in how well they did. It has been so AWESOME seeing that they do remember what I (or other 2nd grade teachers) taught them last year.

I listed this pre assessment as free download in my TPT store. Click on my link to download the quick pre-assessment.

This week each student created their own number line to practice rounding to the nearest 10. I found this activity I my Ready Common Core Math book we are using with the students.  We used bead to move around the number line to determine if by looking we would round up or round down.

I used card stock to make these lines because paper was too thin. I cut the paper into 3” x 12” rectangles. I drew a line half way through to set up the line for the students. Using my document camera we moved each through each step together.

1. Have the student’s estimate where the halfway point is a touch on the number line. (This is a great way to see who remembers estimation!).  Tell them to draw a little dash and label it 50.  Why would I place the 50 in the middle? What do you think I would but at the ends if 50 was in the middle of the number line?

2.  The students will take 2 fingers and draw the same size lines as the 50 to the left and right of 50. They will label those dashes 40 and 60.  Guide them through this activity until it is labeled 0-100.

3. The students will estimate the halfway point between each 10. Have them draw a slightly smaller dash to represent the 5 on the number line. (I did not have my students label the half way 5 marks).

4.  Have them place four even smaller lines before the 5 halfway marks and after the 5 halfway marks.
This activity really only took my students about 10 minutes. 

Give each student a bead. Call out random numbers. Ask the students which ten is it closest to. Anytime you call out a number with a 5 in the ones place remind the students 5 always rounds up.

Honestly, my class had a blast with this. Most of the students kept the line in their desk and have been using it this week as we have been working through our unit.
This is a great way for students to manipulate the number to find the answer. Many students like visualizing how the numbers moved on the number line and how they were closer to one number than the other.
One thing I have learned in the few (very few) years I have taught is that all kids learn at different speeds and learn things in different ways. This is a great way to introduce through a visual aide.

Thanks for reading!
Miss Stetson


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