**Goal:** The goals this week are for you to

- Know some ways of mentally computing with 2 digit numbers

- Know some common alternate algorithms for addition and
subtraction (both student invented and used in other countries)

- Know how to show the standard algorithms for addition and subtraction using manipulatives and make connections between manipulatives and the pencil and paper work.

**Overview:**

What we're going to be doing this week and next and why.

**Assignments:** Please scan as necessary, and put
all assignments in the dropbox.

**Addition
**

Do first:

Do: Try it yourself

Watch: What do other people do?

Assignment 25: Base 5 addition (if this doesn't download correctly, you should right click on the link and choose "Save Link As")

Alternate algorithms and mental math:

Watch:

Read:

Do and read: the Mental Addition investigation 3.2 of the Bassarear textbook

Mathematics for Elementary School Teachers, and read the discussion that follows (pages 134-136 of the 4th edition and pages 131-133 in the 3rd edition)Read: The discussion of Children's Strategies for Addition in the Bassarear Textbook (pg. 136-138 of the 4th edition or pg 133-136 of the 3rd edition)

Assignment 26: Alternate addition algorithms (do, scan, dropbox)

The standard algorithm:

Error patternsWatch: modeling and making connections for the standard algorithm

Read: The Bassarear textbook discussion of the standard algorithm with base 10 manipulative pictures (p. 139-143 of edition 4 or p.137-139 of edition 3)

Assignment 27: Show how to model and make connections for the standard algorithm (video assignment: do, save, put the link in a word document and dropbox it). Guidelines for presenting explanations*It would be great if you did this assignment right away, so I have a chance to give you feedback before you do the similar assignment for subtraction. If you send me an email when you turn it in I'll try to get you feedback right away the next day.

Watch: addition error patterns

Note: I highly reccommend the book "Error Patterns in Computation" by Robert B Ashlock. I have stolen many of my ideas and examples from this book.

Assignment 28: Do the assignment addition errors and algorithmsNote 1: if this doesn't open and print properly, let me know and I'll save it in a different format to send to you

Note 2: some error patterns give you correct answers for some kinds of problems and wrong answers for other kinds of problems, so make sure you check

allof the pretend student work.

**Subtraction
**

Do first:

Do: Try it yourself

Watch: What do other people do? Ways of
subtracting base 5

Assignment 29: Write about it, and do some base 5 calculations (Print, do, scan, dropbox) July 5

**Alternate and student invented
algorithms:**

Read:

Bassarear Textbook section 3.2, with special emphasis on Mental Subtraction, Childrens Strategies for subtraction and An Alternative Algorithm

Some notes teaching and various algorithms

Watch:

More resources (optional)

Assignment 30: Alternate subtraction algorithms(scan, dropbox)

Watch at least one of each pair of examples:

Read: Bassarear: Understanding subtraction in base 10 and
Justifying the Standard Algorithm (4th edition pg. 159-161 or
3rd edition pg 155-156)

Assignment 31: Show how to model and make connections for the
standard algorithm (video
assignment) Guidelines
for presenting explanations

Watch: about error
patterns

Assignment 32: Do the assignment subtraction
errors and algorithms

Note 1: if this doesn't open and print properly, let me know and I'll save it in a different format to send to you

Note 2: some error patterns give you correct answers for some kinds of problems and wrong answers for other kinds of problems, so make sure you check

allof the pretend student work.