Khan Academy Static

Topic D includes lessons 15-17. "Add measurements using the standard algorithm to compose larger units once. Add measurements using the standard algorithm to compose larger units twice. Estimate sums by rounding and apply to solve measurement word problems." EngageNY

8659_Adding_with_regrouping.html

8662_Adding_3_digit_numbers_with_regrouping.html

8661_Addition_using_groups_of_10_and_100.html

8658_Adding_3_digit_numbers.html

8657_Intro_to_place_value.html

8660_Breaking_apart_3_digit_addition_problems.html