CK-12 Foundation
Ck 12: Elem Math: Overview of Addition
[Free Registration/Login may be required to access all resource tools.] The video describes the two basic methods of adding numbers up to twenty. The methods shown are counting on and using tens and ones.
Khan Academy
Khan Academy: Teens as Sums With 10
The video looks at the 1 in each teen number and thinks about what it really means as representing 10, and the pattern of the teen numbers as ten plus some other number.
CK-12 Foundation
Ck 12: Elem Math: One Step Conversions Between Hundreds Tens and Ones
[Free Registration/Login may be required to access all resource tools.] The video uses place value to determine the number of hundreds given a specific number of ones. The video is followed by a series of practice questions to assess...
PBS
Pbs: Odd Squad: Tracking the Number Hog
Olive and Otto learn about using zero in the ones and tens place of numbers to make numbers bigger. Will this help them track down the Number Hog?
Khan Academy
Khan Academy: Place Value Example: 25
This place value video lesson illustrates the number 25 as two tens and five ones. [2:55]