“Mrs. Kerr!!! I’m shopping at Walmart next time!! Mrs. Kerr!!! I spent $80 on cake!!” These are the things I heard students say in my classes all day….. I loved every minute of it! My morning started out terrible, but the minute my students started their activity today…….. my day turned fabulous. Today we rounded and estimated decimals.
I started out reminding my students of place-value; the ones place, tenths, hundredths, and thousandths. We talked about how our number system is based on tens. I drew a rectangle, cut it into ten pieces, and asked them where the middle was. We talked about how anything above five would be closer to the whole rectangle, while anything below five would be closer to none of the rectangle.
I taught them my little jingle (not really mine, I heard it many years ago so I don’t know who to credit). Here’s how it goes…..
Five or more —– raise the score.
Four or less —– let it rest.
I then put an example of rounding whole numbers since they have already learned to round whole numbers. I gave them the problem 329. I asked them what they would do in order to round to the nearest hundreds place (they should have learned this in years past, I’m not sure what grade skill rounding is). They all knew to look at the 2 and that it was less than five and so the three stays the same. I asked them what happens to the two and nine now? They are changed to zeros, so the rounded answer is 300.
I then give them a decimal number. I always start with super easy and gradually use numbers with more digits. I would give them something like 4.8 and ask them to round it to the nearest whole number. I always have my students underline the number they are rounding and then draw an arrow to the number to the right of it. For example, for 4.8 rounded to the nearest whole…..you would underline the 4 and draw an arrow from it to the 8. The 8 is five or more, so you raise the 4 to a 5. It is also important to show that the 8 turns into a 0, and that it is not necessary to have 5.0
After doing several examples of rounding to whole numbers, to the tenths, and to the hundredths I let them go “shopping” at The Kerrville Market. My students LOVED doing this!! I was able to use this “market” for rounding and estimating as well as multiplying whole number to a decimal. I actually could have even used it for dividing a decimal by a whole number, and I probably will next year.