Montessori Activity: Subtraction with Number Rods - Unit Place Value

AGE: 4.5 and up (after the child has worked with the decimal system and addition using the Number Rods. Other subtraction work could have been done prior to using the rods also.)

OBJECTIVE(S): To teach counting and subtraction of the unit place value in a concrete manner seeing the minuend and then taking away the subtrahend.

MATERIALS:

1.     2 sets of Number Rods.

2.     1 subtraction worksheet and a pencil.
3.     1 mat 

PRESENTATION:

1.     Place the 2 sets of number rods side-by-side.

2.     For each set, build the stair using the rods by placing the longest rod at the top and the shortest rod at the bottom.

3.     Explain to the child that addition puts things together and subtraction takes them apart again.

4.     Read the first problem e.g. “10-4=?” to your childf.

5.     Place the 10 rod in front of the child. Select 2 rods which equal 10 (i.e. 6 and 4) and place them under the 10 rod saying 6+4=10.

6.     Then say, "If we take the 4 rod away, how many are there left".

7.     Point to the 6 rod and say, "There are 6 left. We say that 10 take away 4 equals 6"

8.     Take the appropriate number card and place them under the rod 6.

9.     Ask your child to say, “10-4=6” and write the answer on the worksheet.

10.  Repeat this process for other problems using the 10 rod as your minuend.

CONTROL OF ERROR:

1.     Seeing the incorrect alignment of the rods.

2.     Counting the places on the rods.

REFERENCES:

- Shu-Chen Jenny Yen’s On-line Montessori Albums
  http://web.archive.org/web/20050212085156/http://www.ux1.eiu.edu/~cfsjy/mts/math/_link.htm