MATERIAL:

- As for addition without exchanging

PURPOSE:

- To work addition problems with exchanging

AGE:

- 4 and one half years and older

EXERCISE:

- This is a group exercise for a few children. The material is arranged as for the previous addition exercise. One child is put in charge of the golden bead table, another of the large number cards, and a third child is responsible for the small number cards. This problem will include three addends, in order to involve more children in the activity. Again, the sum must not be more than 9999, the limit of the material.
- 3465 +1876 +1389 =
- The teacher takes three trays. She asks the number card person to make the addends 3465, 1876, and 1389 in small number cards and place one addend on each tray. The child does so, making each addend from a separate set of small number cards.

- The teacher hands a tray to each of three children. She asks each child, in turn, to read the numeral on his or her tray. When they have all done so, she asks them to collect the golden beads which correspond to the numeral on their tray. The children help themselves to material and bring it back to the teacher. She does not stop to check the quantities. e assumes the children have brought the right amount. She takes a tray and says, "You have brought 3465." She takes the golden beads off the tray and places them on the mat. She takes the addend and places it at the top of the mat. The teacher takes the next tray and says, "You have brought 1876." She takes the golden beads off the tray and places them beneath the first quantity. She places the addend under the first addend at the top of the mat. The teacher takes the third tray and says, "You have brought 1389." She takes the golden beads off the tray and places them under the other quantities on the mat. She places the addend under the other two addends at the top of the mat. She is careful always to place the hierarchies under each other.

- The teacher indicates the material and says, "Here we have 3465, 1876, and 1389. We will add them together and see how much we have all together. She can do the addition herself or ask a child to add the quantities by pushing them together.

- When the quantities have been added (placed together), she asks one of the children to count the units. (It is wise always to get the child to count the units into the lid of the unit box. There is less likelihood of a mistake and the units do not get lost.) The child counts the units and when he reaches ten, the teacher asks him to take the ten units to the banker and exchange them for a ten bar. The ten bar is placed above the ten bars on the table, where a carrying figure would be recorded in a written problem. It is found that units can be exchanged for ten bars twice. There are no units left over.

- The teacher points out to the children that there are two ten bars resulting from changing units for tens and that these must be counted with the tens. The tens are counted. There are enough to exchange for 2 hundred squares and to have 3 ten bars left. The large number card "30" is placed beside them.

- The hundreds are counted. Ten hundred are changed for one thousand at the bank. The thousand is placed above the thousands on the mat. The rest of the hundreds are counted. There are seven. The large number card "700" is placed beside them. The thousands are counted. There are six thousand so the large number card "6000" is placed beside them.

- The teacher superimposes the number cards to get 6730. She puts them below the addends at the top of the mat. The teacher repeats the problem. "We took 3465, 1876, and 1389. When we added them together, we got 6730." More problems are worked in this way.
- Once again, the sum of the addends cannot be greater than 9999.

3465 addend 1876 addend 1389 addend |

6730 sum |