Students need to learn rounding with mixed decimals to the nearest tenth. This essay describes the process of teaching rounding mixed decimals to the closest tenth. In addition, I have identified examples that are likely to prove difficult for students. The concept of rounding mixed decimals is learnt in elementary school this lesson is therefore is designed for learners in the fifth grade.
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Before proceeding with the lesson, I have to ensure that the learners understand the prerequisite ideas. The basics that learners need to be conversant with before I teach them rounding with mixed decimals include place value, rounding whole numbers and decimals (James, 2007, p. 201).
Understanding the place value enables learners to know a digit’s value depending on its position. The concept is taught from the onset of formal learning and continues to be taught in the middle grades as learners come across large numbers. Understanding the place value would also enable learners to round numbers.
The ability to round off whole numbers is also a prerequisite concept to learning how to round decimals. Students who are incapable of rounding whole numbers can hardly round mixed decimals. Lastly, I would ensure that learners are conversant with the concept of decimals. Students need to be aware that decimals represent portions of a whole. In addition, students should be aware that the whole number lies to the left of the decimal mark while the fraction is situated to the right.
At the end of the session the learners are expected to be able to locate the digit in the tenths position and round decimals to the closest tenth. I will first explain that the first digit preceding the decimal point is the one on the tenths place. Thereafter, I will demonstrate to the learners the digit in the tenths place by circling such digits in several examples.
The learners will then be expected to encircle the digits in the tenths place in the following figures 2.4 and 75.53. I will be moving round the class checking if the learners are able to identify the digits in the tenth place. Knowledge of the digit in the tenths place will enable learners easily locate the number to be considered when rounding mixed decimals to the nearest tenths.
Once the learners are able to locate the digit in the tenths position, the concept of rounding mixed decimals will be taught. The learners will first be taught the rules of rounding up and down. If the digit to the right of the tenths place is greater than four, round up, where the digit is less than five the focal point stands unchanged.
Examples will be given to increase the learners understanding of the concepts of rounding decimals to the nearest tenths. The learners will attempt rounding several numbers to the nearest tenths. First, they will circle the digits in the tenths place. In case they are capable of identifying the tenths place digits, they will proceed to round the numbers as expected.
In tasks where the digit in the hundredths position is less than five, the digit in the tenths place is rounded down. Where the hundredths digit is greater than four the digit at the focal point will be rounded up. At the end of the lesson the learners will be given more tasks to solve on their own. The tasks will provide feedback on their understanding of the learnt concepts.
In some instances learners commit procedural and conceptual mistakes when dealing with rounding decimals. When solving problems involving mixed decimals some students round up the whole number rather than the digit in the tenths position. For instance when a learner is given a decimal of 63.56 he or she may fail to realize that the 5 is in the tenths position and hence may round the number to 64.0.
This answer is incorrect. The solution to the problem should be 63.6 because the 6 in the hundredths position is greater than five; hence, we round up the digit in the tenths position by one unit. If students are misconceived about the digit in the tenths place I would revisit the skill of identifying digits in the tenths position. The learners need to be given more tasks involving circling of numbers in the tenths place.
Some students get confused by the place values assigned to whole numbers when dealing with mixed decimals. For instance, in the number 26.359 some learners will ascribe the place values of tenths and hundredths to digits 5 and 9 respectively. If a learner is misconceived about the digit in the tenths place he or she will incorrectly round the decimal to 26.36.
The digit at the tenths position is the 3 so the correct solution for the above problem is 26.4. If the students are making such an error we will attempt more examples involving circling digits in the tenths place.
James, D. (2007). Start Up Maths Year 4 Ages 9-10. New York: Pascal Press.