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Simple format for teaching rounding - starts with the basics of rounding to 10s; 100s and 1000s. Then uses the same format for teaching decimal places and significant figures. Includes introduction to each part and then questions to practice learning.
This presentation simply teaches students tricks for rounding. There is no conceptual understanding about the value of these numbers or , more importantly, where they fall on a number line. Students need to use the value of the number and the required place for rounding to determine the two possible answers (i.e., Rounding 4,359 to the nearest hundred - the two possible answers are 4,300 and 4,400 because those are the two hundreds this number falls between on the number line.) Then, they need to determine the midpoint between those two possibilities and determine where the original number would fall in regards to the midpoint (i.e., 4,350 is the midpoint between 4,300 and 4,400 and 4,359 falls after the midpoint. So therefore it is nearer to 4,400 and would be rounded to 4,400.) Tricks get students to the answer quickly but often lead to misconceptions or confusions...and what does it really mean if a student says the number in the tens place was 5 and I know if it is 5 or more I round up so the answer is 4,400. HUH?? Where is the mathematical language to demonstrate understanding in a response such as that? We need to dismiss the tricks and teach for conceptual understanding. Oh, and wouldn't it be cool if, after students developed deep conceptual understanding, they used repeated reasoning to derive the rule...if the digit in the place value that determines the midpoint is less than 5 then it is less than the midpoint and would round down, but if the digit it the place value that determines the midpoint is equal to or greater than 5 then the number would fall at the midpoint or beyond and would therefore round up. No tricks needed, they can determine the rule on their own without tricks once they have developed deep conceeptual understanding.
A fantastic powerpoint presentation based on the topic of rounding. I like this because it is colorful and engaging to pupils, and gets the idea of rounding across nicely to the pupils. Ideal as a main resource in a lesson on rounding, and touches on sig figs too.