Decimals Operations Addition (lesson 1)

Teacher can choose to use bead bars for this lesson to help make an impression for the difference in values.
1. Select the first problem: 8.38 + 6.75
2. Make the top addend with cards, and place it to the left of the board. Then make the second addend with cards, placing it under the first. Place the cardboard strip under both.
3. Form the first addend with beads and disks on the board. Then form the second addend on the board, leaving a space between the two addends.

4. Begin adding with hundredths: 8 + 5 = 13. Exchange the hundredths for a tenth, leaving three thousandths. continue adding tenths, then units- exchanging when necessary, until the sum is reached. When the addition is complete, get the small cards corresponding to the sum, and place them under the addend cards.

NOTE:

Provide examples that offer many opportunities for exchanging, e.g., 0.999999 + 0.000001
Provide other problems with addends having unequal numbers of decimal places, Italic textPointing out the importance of lining up the decimal mounts inside the proper place values. Example: 32.285 + 7.94
Provide other problems with more than two addends or with addends written horizontally, e.g. 52.74 + 6.5 + 23.88 =

Most students will work with this material for a very short time, because they will be able to internalize the procedure and proceed abstractly.

Teacher guided; lining up the disks in the proper decimal place values.

Participating with the new knowledge helps move the concrete experiences toward abstract thinking

To make a visual, auditory and kinesthetic impression upon the student on how to perform operations with decimals.

Alternative: Use bead bars instead of beads and disks.

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