Your assignment is to explain addition.  Specifically, you must:

• Make up a 3-digit subtraction problem, for which you must exchange twice (tens for ones, and hundreds for tens).
• Show how to solve your subtraction problem by:
• showing what to do with manipulatives (base 10 blocks or stamp game tiles).  You are required to do this using a take-away model, and not a compare model (max half-credit if you start with building both the subtrahend and minuend)
  
• showing how to record your manipulative work in the usual pencil-paper way
• explaining in words what you are doing and why, so that the manipulative work and the pencil-paper work fits together and makes sense

You have the option to do this

• On paper, with the manipulatives, the numbers, and the words you would say written out in full.  No points for artistry, but don't skip steps! OR
  
• On video, using these resources:
• Use the manipulatives in one of these SMART Notebook files: Base 10 blocks; Stamp Game.  SMART Notebook is installed on the computers in WEB.
  
• Record yourself using Screencast-o-matic
• Make sure you have a working microphone (make a quick test video to check it)

Tips for getting a good grade:

• Choose good numbers:
  
• Choose numbers that will give you a good variety of differences in the columns
  
• Make sure your numbers fit the criteria for the problem (exchange twice)
  
• As much as possible within the guidelines above, make sure that all of the digits are different--this makes it easier to keep track of what's going on (if there's more than one 4x5 in your problem, there's a confusion about which is which.  I highly reccommend not starting with 1's in the minuend, because it makes it easy to make mistakes when you are recording the exchanges)
• Use correct language:
  
• place value language; know what place value you are working with, and name it correctly.  Name place values wherever it is not undesirable to do so.
• parts of an operation: the important words for this minuend, subtrahend and difference.  You can also use the words take away and minus.  Make sure you use them in the right order: Take away the subtrahend from the minuend, or take the minuend minus the subtrahend.  Don't get them backwards.
  
• Don't use "borrow" or "carry", instead use words like: trade, exchange, rename, regroup and/or record
  
• Explain the trading steps explicitly.  For example: Now we trade 1 hundred for 10 tens, and that's a fair trade because 100=10 tens.
• Go from concrete to abstract
• If you have both a manipulative and a number way of showing the algorithm, do each step first with the manipulative, and then with the numbers, and
• explain each step in the number work as a way of recording what is happening with the manipulatives
• Make the connections step by step--don't wait until you have done the whole problem with the manipulatives and then make the connections: do a step with the manipulatives, and then the same thing with the numbers.  (My husband describes one of his friends' masters thesis as dropping a wall on the reader one brick at a time.  I want you to drop an algorithm wall, very carefully, on your listener, one brick at a time.)

Examples to watch: me explaining this. Me explaining this again.   A student explaining this.

Tips for getting the technology to work:

• Here is a vid of me using Screencast-o-matic (on a Mac--the computers with microphones in WEB are Macs).  If screencast-o-matic doesn't work in WEB, try a different web browser (Firefox, Explorer and Safari are web browsers).  If screencast-o-matic doesn't work on your personal computer, try updating your Java.
  
• Here is a vid of me using SMART Notebook
• Here is where to download SMART Notebook if you want to do this on your own computer.  The activation license number is on the D2L site (on the welcome page, it is its own news item)
• If you are doing this on your own computer, I recommend starting with screencast-o-matic, and if that does not work the way you would like it to, that you next check out Jing or (what I use most of the time, though it involves an extra step) Blueberry Flashback Express.
• When you are done, you should have a file on your computer (hopefully somewhere you can find it--if you are in WEB, and you can't find the file, get one of the technology helper people to show you how to search for it by name).  The file should be something.mp4 if you made it and exported it with Screencast-o-matic.  If you used Jing, the file name should be something.swf.  Upload this file to the D2L dropbox: addition explanations.