Marie Lewis work blog week 6

     My fourth graders are just wrapping up practice with mean, median, mode and range.  On their summative test, a student was asked to find the mean of the values 13,12,11,10,9,9

The student added up the six values of the number. She then added the sum six times on paper.  With that second sum, she divided it by 6. The student took one extra step in finding the mean, skewing her answer and arriving back at her initial sum.  The student knew she was supposed to add the values and divide by the number of values by six, but she added the values too many times. 

Her work shows me she does not have a clear understanding of what a mean, or average is.  I do not think she compared her answers to the set of values given at the beginning of the problem. The number 64 is an outlier to this set of data and had she known, she may have taken a step back to think about the answer she had put down. 

     I feel it would be beneficial to have a similar conversation I had with my last student about this.  I would ask her to explain what she thought when she was solving this problem.  I would give her authentic models of mean that occurred in her life, helping her gain a better understanding of the mean.