Lesson 3.4: Alternate and student invented algorithms for addition and subtraction

Lecture: Text

Videos: Note, this time I have done each small piece separately), so if you want to go back and re-watch an algorithm, you can watch just one of the videos

Student invented/mental math algorithms
Addition Subtraction
Adding on in chunks using multiples of 10 and 100 as bridge numbers Adding up to the minuend in chunks using multiples of 10 (and 100) as bridge numbers
Add in place values and combine Subtract in place values using negative numbers, the negative numbers algorithm
Add highest place values and compensate Subtract highest place values and compensate
  Shift the number line
Teaching/Scaffolding algorithms
Expanded addition Break into place values (expanded subtraction)
  Trade first subtraction
Algorithms that are standard in other countries and/or used to be common here
British standard way of writing addition Equal additions subtraction algorithm