Numbers to 40
Counting
As in learning to count to 10 and 20, students will first learn to read and write the number symbols and number words for numbers up to 40. Picture cutouts again are used to display the quantity while the number symbols and number words are taught alongside the quantity.
The students are progressively taught how to count to 40. First they are introduced to counting up to 30, then to 40 by making ten first. Using picture cutouts and number cards, students will learn to recognize the logic ad pattern of counting beyond 20 is the same as that of counting beyond 30.
Students will learn the number sequence and the concept of more than and less than through activities involving finding a number 1, 2, or 3 more or less than a given number. After understanding these concepts, students will be able to compare numbers and arrange a given set of numbers in increasing or decreasing order with more ease.
Addition and Subtraction
Because the students have learned how to interpret a two-digit number in terms of tens and ones, this better prepare them for addition and subtraction with and without renaming.
Students are first presented with cases of addition and subtraction without renaming. Addition and subtraction without renaming can be demonstrated using a combination of picture cutouts and number bonds. Using picture cutouts, students are shown that such addition and subtraction take place within the objects not grouped within a group of ten and there is no change in the objects grouped within groups of ten. Corresponding number bonds are used to show what happens at the abstract level. The addition and subtraction are shown to affect the number in the ones place while the number in the tens place is unaffected. The converse is shown to occur when the addition and subtraction of a ten takes place.
Students will also learn to apply the count on and count back method of addition and subtraction to adding or subtracting 1, 2, or 3 from a given number for numbers up to 40.
When showing addition involving renaming using rectangle cutouts, students need to learn how to make 10 to derive an answer. With subtraction, students will learn that they need to subtract from ten to derive the answer. Demonstrations of addition and subtraction with renaming involve the use of rectangle cutouts before moving on to demonstrating them at the abstract level using number bonds.
Comments: