Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _.
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Category Videos

Not Right For WatchKnowLearn
Ages: 9  16
2714 Views:

In this video the instructors subtract negative numbers. They start with addition using a number line they show how to subtract negative numbers. They show this with a few examples. Then they move onto subtracting a negative number. They do some exam...ples using the number line and doing the problem at the same time. They then look at how subtracting a negative number is the same as adding a postive number. A few examples are then done. The video is good quality and good for all students as review or initial learning of the concept. (05:54)
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July 31, 2009 at 03:45 PM


Not Right For WatchKnowLearn
Ages: 8  16
3492 Views:

This video indicates it is for prealgebra, however this would be good for anyone who is reviewing subtraction. In this video they show how to subtract using the number line, this includes negative numbers. They do this using many different examples.... Then they do a word problem using the number line and then equation form. Once again they do a few examples. Video is good quality and it is good for all.students as review or initial learning of the concept. (06:56)
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July 31, 2009 at 08:44 AM


Not Right For WatchKnowLearn
Ages: 8  14
3169 Views:

This video indicates it is for prealgebra, however this would be good for anyone who is reviewing or learning place value. This video has humor, which helps make the lesson fun. Video shows how to use the number line, shows how to use the number lin...e where the problem has more than two addends. Then they show how to add in different order by grouping numbers, knowing which numbers add up to 10 to make it easier. This video gives many examples to reinforce the lesson taught. Video is good quality and good for all students as review or initial learning of the concept. (09:21)
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July 31, 2009 at 08:00 AM


Not Right For WatchKnowLearn
Ages: 5  11
2213 Views:

The goal of this puzzle is to put three numbers inside of each circle so that they add up to 0. Solve the puzzle by dragging the black numbers to the blank spaces. You cannot move the blue numbers.
When the three numbers inside any circle add up to ...0, the circle changes color.
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May 15, 2010 at 07:29 PM


Not Right For WatchKnowLearn
Ages: 7  12
2053 Views:

The goal of this puzzle is to put three numbers inside of each circle so that they add up to 21. Solve the puzzle by dragging the black numbers to the blank spaces. You cannot move the blue numbers.
When the three numbers inside any circle add up to... 21, the circle changes color.
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May 15, 2010 at 08:07 PM


Not Right For WatchKnowLearn
Ages: 5  10
3272 Views:

Begins with a review of addition (in simple terms) with visual support. Number line is also used to demonstrate principles. (08:32)
April 3, 2009 at 01:34 AM


Not Right For WatchKnowLearn
Ages: 6  8
2214 Views:

Mr. R.'s math song about addition fact 5 + 5. (02:29)
May 19, 2010 at 08:01 AM


Not Right For WatchKnowLearn
Ages: 5  8
2287 Views:

Mr. R.'s salsa math song about adding double number fact, 5 + 5 = 10 and counting in English and Spanish. See more math resources at http://mathstory.com/
May 19, 2010 at 08:07 AM


Not Right For WatchKnowLearn
Ages: 8  14
3019 Views:

The instructor uses humor to demonstrate how to subtract numbers on a number line. The video features a dual screen, and sometimes a threepart screen for demonstration. (06:23)
March 18, 2010 at 08:40 PM


Not Right For WatchKnowLearn
Ages: 8  11
2649 Views:

Using one, two, and threedigit numbers, students learn how to subtract numbers without borrowing in columns. They use their
knowledge of number families to find the missing numbers in tables using addition and subtraction. Finally, students lear...n key words to look for in word problems that signal addition or subtraction operations.
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June 2, 2010 at 12:17 PM
