Materials Needed: DN Worksheet, white board, dry erase markers, and IND worksheet
Vocabulary: estimate, compute, rounding / front end rounding, approximation, regrouping, about, closest
Do Now (3 -5 min): Teacher hands a DN Worksheet to every student and asks the students to complete the worksheet independently.
Opening (2 -3 min): Teacher quickly reviews answers to the Do Now and then says, “Today, we are going to continue to reviewing rounding whole numbers. We know that rounding whole numbers is one strategy we can use when estimating an answer. Yesterday we reviewed rounding whole numbers to the 100,000 place. By the end of this lesson, you will be able to round whole numbers up to the hundred millions.”
Direct Instruction (10 min): Teacher begins “Ok! Let’s quickly review the place and value of each of these digits before we begin. [Teacher writes 397,172,458 on the board] and asks:
Who can tell me which digit is in the ones, tens, hundreds, thousands, ten thousands, hundred thousands place, millions, ten millions, and hundred millions?
How much are each worth?
Teacher should draw the place and value out on the board.
Teacher continues, “Awesome! Ok, so we going to round to the nearest hundred millions place. We already know how to round. Who can remind me of the rounding up and rounding down rules? [We round down if the number is 4 or below; we round up if the number is 5 or above. Awesome! So, when we round we are determining which number a given number is closer to within the 10s system. Let me show you how to do it when we are looking at the hundred millions place.” The teacher writes the following on the board.
675,581,622 = ________ [700,000,000]
490,241,111= _________ [500,000,000]
792,290,513 = ________ [800,000,000]
446,960,000 = _________ [400,000,000]
331,711,861 = _________ [300,000,000]
The teacher continues, “I am going to round these numbers to the nearest hundred millions place. Remember, it is very important to look closely at the number so that you always remember which place you are rounding to. I suggest that you underline the place value that you want to round to when you are asked to round numbers that are this large. For these five examples, I am rounding to the nearest hundred millions place, so I will underline all of the numbers in the hundred millions place.” Teacher underlines the hundred millions place in each problem on the board.
Teacher continues, “Watch as I round these numbers. The first example is, six hundred seventy five million, five hundred eighty two thousand, six hundred twenty two. Ok 6 is in the hundred millions place, and 7 is in the ten millions place. I know I round up if the number in the ten thousands place is 5 or more. So I am going to make the 6 a 7 and the rest of the numbers 0, so I will have 700,000,000.” The teacher should continue thinking aloud for each example.
Guided Practice (10 min): The teacher continues, “Ok, so now it is your turn! We are going to practice rounding numbers to the nearest hundred millions. I am going to write five problems on the board for us to complete together, then you will get a chance to show of your skills independently. Let’s get started”
581,760,569 = _________ [600,000,000]
742,234,631 = __________[700,000,000]
309,152,956 = ________ [300,000,000]
588,638,993 = ________ [600,000,000]
864,552,736 = _________ [900,000,000]
192,716,721 = _________ [200,000,000]
Independent Practice (10 min): The teacher hands out the IND worksheet. Students are asked to complete the worksheet independently and turn it in.
Closing (2-3 min): Teacher calls the attention of the students back toward the front of the class to ask what they learned about.