Our addition strategies so far:

Add Zero, Add One, Count On/Up (+2,3) 

https://www.mathplayground.com/math_monster_addition.html

Friends of Ten/Make 10 (choose the number 10)

https://www.abcya.com/games/math_lines_addition

You can find these links under the tab "Web Links" if you look back another time when this post isn't at the top.