Why I Don't Teach Rounding Tricks (anymore!)



My very first year teaching, I taught a self-contained special education class of 16 students in a New York City public school.  Did you know you can do that with absolutely no experience or qualifications?  Yeah….

I had absolutely no idea what I was doing, but I sure as heck tried.  But, when it came time to teach rounding to my 3rd -5th graders who had little to no place value understanding, I thought I was so clever.   I got a yard stick and a hula hoop, gave each child a slate with a number on it, made a human-sized big number to round,  and taught them this trick:

1.    Circle the place you are rounding to.  (That person got in the hula hoop.)
2.    Underline the place to the right.  (Yep, that’s what the yard stick was for…)
3.    The underlined number (person with the stick) is the decider.  If they are strong enough (5 or higher), they can order the one in the hula hoop to go up to the next digit.  If not (0-4), then they cannot do anything. 
4.    The circled number (person in the hula hoop) does not like being bossed.  They get annoyed and turn everyone behind them (to the right) into zeros. 

Obviously, these steps work, and if students follow them, they they will be able to round.  But I wouldn’t say that they LEARNED to round or that they UNDERSTAND rounding… that’s a whole other thing.   But, in my naivety, I thought that, if the kids got the right answer, they understood it.  I kind of wish I could go back and super apologize to that class…

Here’s what I missed:
Teaching kids to round isn’t really about teaching them to get the answer (like most of math!).  It’s an uber important part of the puzzle in constructing place value/ base ten concepts.  When I taught then tricks instead of helping them truly understand rounding, I was robbing them of crucial time spent working with place value and understanding how our base ten system works.  (And believe me, I paid for this mistake later on, when I tried to teach estimation, computation, word problems, and every other concept that relies on a solid place value understanding.)


Here's a better idea: I should have helped my students discover rounding patterns so they could generalize and extend their understanding of how the base ten system works.   

I also should have helped them develop a stronger concept of what rounding actually is, why we use it, and how it works.




Yes, teaching “tricks” is fun and sometimes helps kids feel more successful.  If I could do it again, I would teach the rounding tricks AFTER students had a solid understanding of how to round without using the tricks.  That way, it’s like coming up with a shortcut for something you already know how to do, instead of skipping over the heart of the concept to get to the ‘trick.’


For more ideas on a better way to teach rounding, click here for my rounding unit.


Happy (rounding) Teaching!!

Christine Cadalzo