Monday, May 30, 2016

Sir Cumference and the Roundabout Battle

I've been a huge of Cindy Neuschwander's Sir Cumference series for quite some time. Sir Cumference and the Roundabout Battle does not disappoint. It provides a fun tale, while demonstrating an important math concept rounding.

In this episode we find Sir Cumference's steward, Edward Rounds working with his son, of the same name on the accounts. To avoid confusion the two are known as Rounds 1 and Rounds 2. While the younger, Rounds 2 enjoys counting, double digit adding is not his strength and he struggles with how to quickly add the columns of numbers to provide accurate counts that Sir Cumference and his men rely on in doing their daily tasks. His father emphasizes that while it is important to be an accurate counter to be steward, the ultimate purpose in counting is to supply an inventory that will be useful to those needing to use it in the castle. Accurate data from counting is essential for the inventory to be correct, but without finishing the final step in adding up the numbers the inventory is not very practical for those who come to ask for information.

Rounds 1 and 2 discuss how much easier it is to count with round numbers, but his father does emphasize the need for an accurate count. As the story continues, Rounds 2 stumbles upon an invasion force and now the inventory is more important than ever, for Sir Cumference needs to know how many bows and arrows he has available to fight off the incoming forces. Rounds 2 panics because he has not had the chance to finish adding all the columns. Rounds 2 lacks the time to add all the columns so he grabs a tape measure to help him figure the closest friendly 10 for each entry. Once he has his estimates, the columns are much easier to add. He is then able to present a rounded count just as the invasion force is arriving. It is looking scary for Sir Cumference's forces, but help arrives from an unexpected resource and all is resolved in favor of the heroes.

This was a great way to demonstrate a practical use for rounding. It also used larger numbers that demonstrated a need for rounding. One issue I struggled with as a child is we started rounding with problems I could answer without rounding. Why do the extra work of rounding when I know the "real" answer. This presents both Round 2 and the children with real practical reasons to round numbers.

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