In this lesson for 1st grade, I show with a visual model how EASY it is to add sums such as 23 + 6 or 54 + 3 mentally.
You simply add the ones, and the tens do not change. To solve 23 + 6, add 3 + 6 = 9, and the answer is 29. Children will easily get this idea when shown a visual model.
We also add numbers "in boxes" - in other words, by writing one number under the other, or adding in columns.
The lesson also includes an initially silly word problem (by Mathy my mascot mammoth), and some comparisons that require a bit of algebraic thinking.
Note that the sums in this lesson do not require regrouping (carrying) - we study that process in another lesson which is found at https://www.youtube.com/watch?v=5EPR7OG_PL8
Check out also my other videos at http://www.mathmammoth.com/videos/
Tagged under: -digit,-digit addition,mental math,addition,1st grade,math
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