Tuesday, April 7, 2015

Open Number Lines

Hi guys! It's Meredith from Creativity to the Core. Lately in third grade, we've been testing testing testing and haven't had much time for anything else. Can you relate?!? I am SO ready for it to be over so that we can have some fun!
But today, I wanted to stop by and share a little tip with you. It's super simple, but has helped my students immensely! Read on to learn how I use open number lines in my classroom.
(These examples are shown on plastic disposable plates. I just love this affordable option for student white boards! Just use a piece of felt or a tissue to wipe them clean. In class, we often also use white boards and chart paper when showing our examples.)

Students always seem to struggle with elapsed time. It's a hard concept for them to wrap their brains around because it is so abstract.

This year, I have even found some students who have severe deficits in the basics of telling time. These students are just now mastering time to the minute, so I knew they would really struggle with elapsed time. My coach introduced me to this great way of mapping out elapsed time. I wish I had learned it this way in school, because it just seems so obvious! Here are the steps...

Example word problem:
Jake left his house at 1:15 PM. He went to Hunter's to swim in the pool. Jake returned home at 4:28 PM. How long was Jake away from home?

When you are first teaching this, make sure to model each step. Model, model, model. Students need to be aware of how to draw the number line. They need to understand WHY they are labeling certain parts and WHAT the labels mean. 

When students have reached the ending time, they simply circle the times above the number line and add them all together. They have found the elapsed time!
love using this method because: 
1) students always think it's a "cool trick" 
2) it allows students to actually see the time that has elapsed
3) it works whether students are trying to find the start time, the elapsed time, or the end time

Here are some examples of one of my students using the open number line to find the end time:
Breaking down time into easy to add chucks. 
Adding time below the number line can be helpful for some students.
All finished! Color coding is SO helpful when breaking down the word problems!
If you are teaching elapsed time, you can check out these centers to help students gain more practice in finding the start time, elapsed time, and end time in different situations. Also, be sure to grab the first set FREE here! The open number line strategy will work perfectly with these center activities! Have a great week!


  1. Love the plate idea for white boards.. Thank you!! :)
    My kiddos have trouble with elapsed time also.

  2. That's exactly how I taught elapsed time! It was the only way to reach my struggling kiddos. Thanks for the freebie!
    Stories by Storie

  3. Thank you so much for the idea! I've been stressing about elapsed time and this just makes the concept so simple!