Open Number Line

This weekend we have some homework to do.  We are interviewing our family members to find out their ages.  As part of our Addition and Subtraction to 100 Unit in Mathematics, we have been practicing a variety of strategies to find sums and differences.  Last class we read the book El Bisabuelo Gregorio.  The boy in the story, Carlos, is celebrating his eighth birthday.  He becomes very curious about how old his family members were when he was born when his great-grandfather comes for a visit.  Carlos figures out that his great-grandfather is 87 years old!

The latest strategy that we have added to our list of addition and subtraction strategies is 'use an open number line'.  This strategy has been especially helpful to students who are having difficulty with subtraction.  This tool/strategy allows them to use/visualize/record differences between numbers by either 'jumping/hopping' forwards or backwards (adding or subtracting).

Students decide upon the 'jump' - usually to the nearest 'friendly' number, and continue until they 'land' on their target number.  Recording their 'jumps' is very important.  They add up the 'jumps' to find the difference between the two numbers they are investigating.
On Monday, students will use their collected data to find the differences in ages between themselves and their family members.  The numbers collected are important and unique to them and provide a meaningful context to practice this new strategy.