With the AL dot in the upper right corner, tilt the abacus to the right until all the beads are on the right side. This is called "clearing" the abacus. On the top wire of the abacus, push the 10 beads all the way to the left. This is called "entering 10." Move the bead farthest to the right about 1/2 inch away from the rest of the beads. They can briefly place their finger in the empty space between the sets of beads. This represents 9 + 1 = 10. The student should state the addition fact. Move a second bead 1/2 inch to the right until it is next to the first bead. This represents 8 + 2 = 10. The student should state the addition fact. Give the student a blank worksheet (__ + __ = __) for them to write all the addition facts that make 10. They should use their abacus to help them fill in the worksheet.
Prepare a worksheet with the addition facts that make 10, but mix up the order and leave the second addend position blank (6 + __ = 10). Clear the abacus. Read the problem aloud and ask the student to repeat what you said. Enter six beads on the top row, and 10 beads on the next row. Ask the student, "How many beads are needed to make the number on both wires equal?" They can count the missing spaces, or they can move the three beads over as they count. Give them the worksheets to fill out with the help of their abacus. For more practice, give the students some oral problems to solve.
Make cards for each player with one of the numbers one through nine on each card. Make an extra number five card. Each player should spread her cards face up on the table, and clear her abacus. Each player should pick up a card, such as "2," and enter that number on the top wire of her abacus. Ask her to slide the remaining beads in the row to the left, placing her finger in between the two sets of beads. Ask her, "How many beads do you need to make 10?" She will look at her abacus and answer, "Eight." Tell her to find the eight card and place it with the two card. Continue to find pairs.
The Commutative Property of Addition states that the addends in an addition problem can be in any order, a + b = b + a. Clear the abacus. Ask the students to enter 10 on the first wire, and move one bead to the right 1/2 inch. They should briefly place their finger in the empty space. Ask them to use the Commutative Property by switching the order of the addends on the second wire. They should enter 10, and move 9 beads to the right. They should briefly place their finger in the empty space. They should be able to see that changing the order of the addends does not change the answer. Ask them to continue the same process with all the addition facts that make 10.