• Subtraction tool kit    
     
    GOAL: Moving students toward computing problems quicker, easier and with a better UNDERSTANDING (number sense and place value)
     
    Click on mini movie to see the strategy in action by a 2nd grade student...

     

    • Writing an equation

      subtraction_write_equation.wmv, 1.00 MB (Last Modified on May 1, 2012)

    • Solving with pictures

      subtraction_pictures.wmv, 3.63 MB (Last Modified on May 1, 2012)

    • Counting up with tallies from the smaller number

      subtraction_tallies.wmv, 1.30 MB (Last Modified on May 1, 2012)

    • Using ten frames

      A ten frame is available on the main problem solving page. You can use pennies, buttons, beans or anything else to work on it.
      subtraction_tenframes.wmv, 1.88 MB (Last Modified on May 1, 2012)

    • Using base ten blocks

      You can use the virtual manipulative library at home. Students can also draw them.
      subtraction_baseten.wmv, 1.16 MB (Last Modified on May 1, 2012)

    • Counting by 1's on the 100 chart

      There is a 100 chart available on the main problem solving page.
      subtraction_hundred_byones.wmv, 1.31 MB (Last Modified on May 1, 2012)

    • Counting back by 10's and 1's on the 100 chart

      subtraction_100bytens.wmv, 958.08 KB (Last Modified on May 1, 2012)

    • Number strings (negative number)

      An easier way is to leave the first number whole and ONLY break apart the second number.  You may need to break it apart several times.
      subtraction_numberstring.wmv, 933.65 KB (Last Modified on May 1, 2012)

    • Open number line adding it up

      This strategy uses addition to solve a subtraction problem.
      subtraction_opennumberline_addingup.wmv, 936.29 KB (Last Modified on May 1, 2012)

    • Open number line with little jumps

      Since we have created this video, we realize that the larger numbers on the numberline should always be on the right.  So the student should have written 88 on the right side and then worked right to left like subtraction would do on a number line.
      subtraction_opennumber_littlejumps.wmv, 894.89 KB (Last Modified on May 1, 2012)

    • Open number line with big jumps

      Students need to be careful not to jump beyond the target number.  See next video.
       
      Since we have created this video, we realize that the larger numbers on the numberline should always be on the right. So the student should have written 88 on the right side and then worked right to left like subtraction would do on a number line.
      subtracton_openwithbigjumps.wmv, 1.09 MB (Last Modified on May 1, 2012)

    • Open number line with big jumps going too far

      This video also has the numbers on the wrong place on the numberline.   The smaller numbers should be on the left and the larger numbers should be on the right. It seems like we learn each year along with the students.
      subtraction_opennumberline_toofar.wmv, 561.47 KB (Last Modified on May 1, 2012)

    • Counting back

      Most second graders are successful with this by the end of the year.
      subtraction_countback.wmv, 1.28 MB (Last Modified on May 1, 2012)

    • Landmark number

      subtraction_landmark.wmv, 831.61 KB (Last Modified on May 1, 2012)

    • Compensation- rounding

      subtraction_rounding.wmv, 1.64 MB (Last Modified on May 1, 2012)

    • Derived facts

      subtraction_derivedfacts.wmv, 1,012.18 KB (Last Modified on May 1, 2012)

    • Equal additions

      High level students love this one.  They need to be careful to round the 2nd number (the number being subtracted) to the nearest ten.
      subtraction_equaladdition.wmv, 1.05 MB (Last Modified on May 1, 2012)

    • Standard Algorithm with understanding

      This is NOT taught until 3rd grade, please let your child try other strategies that are more age appropriate. They CAN do other strategies even with large numbers. 2nd grade students will try to act like they can't because they would love their parents to do their work at home. Introduction too soon causes confusion and students often regress in many other areas in math.
      subtraction_standard.wmv, 953.19 KB (Last Modified on May 1, 2012)
    note: If you have a mac computer, you need to right click on the file and save to your computer.  Then you need to change the file extension from .wmv to .mov so that you can view the videos.