Ray's New Primary Arithmetic by Joseph Ray Ray's New Primary Arithmetic by Joseph Ray    

Lesson 14: Add Three Numbers Up to 20

Directions

Follow the step-by-step instructions below to teach the lesson.

Progress to the next lesson when children master the current lesson.

Value mastery over speed of progression.

Steps

STEP 1

Teach children to recognize and combine groups of physical objects up to 20 (without counting). Use a variety of objects that interest children such as coins, books, dinosaurs, action figures, cars, and stuffed animals.

• Show children groups of 1-20 physical objects and have them call out the corresponding number.

• Have children show you a specified number of objects without counting.

• Combine objects per the table above and then immediately separate these groups again into their component parts. For example, 8 pencils and 10 pencils and 2 pencils, 5 coins and 4 coins and 4 coins, and 7 cars and 7 cars and 6 cars, etc.

• When children are ready, call out problems from the table and have children combine and separate the object groups themselves.

• Children must perfectly master the operations listed in the table before proceeding to the next step of the lesson.

STEP 2

Children add objects they can't see, but can imagine (bears, mountains, trees).

• Using the table below as a guide, ask children to call out the answer to questions such as, 'How many are four shoes and four shoes and three shoes?' and 'How many are five frogs and four frogs and four frogs?'
• Continue to practice until children can recite each operation in the table with great accuracy and rapidity.

STEP 3

In this step, do not mention objects. Children add numbers directly.

• Using the table above as a guide, ask children to call out the answer to questions such as, 'How many are ten and seven and three?' and 'How many are five and five and five?'
• Continue to practice until children can recite each operation in the table with great accuracy and rapidity.

STEP 4

Direct children to write and recite the addition problems in the table above. For example, children write and recite:

• 10 and 5 and 5 are 20
• 10 plus 5 plus 5 is 20
• 10 + 5 + 5 = 20

Repeat for each combination in the table until the children master the tasks.

STEP 5

Assess mastery by reading aloud the word problems listed below and having the children mentally compute and recite the solutions.

If children have difficulties, repeat the prior steps and then reassess.