Number Lines for Rounding Numbers

Here's a snippet from our lesson on rounding today:

One of the largest animals ever found was a blue whale that weighed 183 tons.  Is 183 tons closer to 100 tons or 200 tons?

Which two tens is 183 between?  Which ten is it closer to?

After students talked in their table groups to figure this out, they attempted to convince the rest of the class their answer was right.

Here are the results of one class' discussion:

Most groups mentioned comparing 183 to a half-way number (150 when rounding to the nearest hundred and 185 when rounding to the nearest ten), then compared the distances to the nearest multiple.

I was very impressed with one group, who shared that when rounding 183 to the nearest hundred, first, they found the closest landmark/benchmark number (180).  Then they thought about the distance to the nearest multiple of 100 in tens.  Do you think this strategy would work for any number you're trying to round?  Why or why not?  If you can think of an example of when it wouldn't work, tell us about it in your comment.

How to Comment Easily and Safely on Our Class Blog

Welcome to our class blog!  Here we post class  news, student work, strategy explanations, photos of class happenings, and web resources connected to what we're studying.  Be sure to follow our blog by entering your e-mail address in the top right corner, so you don't miss anything! 

Comments bring our blog to life!  We encourage students respond to posts; it's fun reading conversations in the comments.  Read this post, leave a comment, and earn your first Chief Cash for participating on our blog.  :-)

If you're new to blogs and commenting, check out a post from another teacher whose class blogs.  Her students gave some great tips for leaving comments!

To comment on a post, first, scroll to the bottom of the post.  If no one has commented, click on the link that says No Comments.  If others have commented, then click on the link that says the number of comments.  After doing this, you should see a box like this:



Where it says "Comment as" and asks you to "Select profile", you can comment using your first name only by selecting "OpenID URL"


Then just type in your first name.


After clicking "Continue", your first name should now appear on the drop down menu.


Select your first name, type your comment, proofread, and publish it!

Students, how do you feel so far about moving upstairs to fourth grade?  What have you been enjoying?  What has been challenging?

Remember when commenting, you can also ask questions, give a compliment, or add information when you respond to others' comments.  :-)