Perhaps the most important skill for fourth graders is that of multiplication. A key way to teach multiplication is via multiplication sentences. Unlike a traditional sentence, multiplication sentences use numbers and symbols to express a statement. By learning multiplication sentences, fourth graders learn how multiplication and addition relate to each other.
Parts of a Multiplication Sentence
A multiplication sentence consists of two parts: one part is a mathematical expression and the other part is the product. In multiplication, a mathematical expression is the part of the sentence that comes before the equal sign. The mathematical expression contains the factors and the multiplication symbol. For example, in the sentence "2 x 8 = 16," the "2 x 8" portion is the mathematical expression. The mathematical expressions doesn't include the answer, which is also known as the product. In the multiplication sentence "2 x 8 = 16," the two and eight are factors and 16 is the product.
Create Sentences Using Arrays
Before students can learn about multiplication sentences, they must understand the concept of an array. An array consists of a set of numbers or objects arranged in columns and rows -- usually on a grid. This makes it possible to count the number of columns and to multiply the resulting value by the number of rows. By using multiplication, students don’t need to manually count each item in the grid. This forms the basis for multiplication sentences and prepares students for more advanced math. For example, show the students an array that has nine objects in each row, and a total of six rows. Show them that they can count each individual item in the array, or they can multiply nine times six for a product of 54. For example, the complete sentence looks like "9 x 6 = 54."
Creating Multiplication Sentences
Multiplication sentences serve a crucial function in enabling fourth graders to learn how to use math in a practical way. The ability to construct a multiplication sentence extends beyond the classroom, by preparing students to calculate large numbers of items. A student who knows how to create his own multiplication sentences can look at a five-by-five grid of items and will know that the grid contains a total of 25 items. Ask the students to count the number of rows in a picture and then write that number down on their papers. Then, write a multiplication symbol and write the number of columns after the symbol. In a five-by-six grid, students should write "5 x 6," with "x" as the symbol for multiplication. Once they do this, tell them to write an equal sign and solve the problem. For example, a correct multiplication sentence for a five-by-six grid of items looks like "5 x 6 = 30."
When to Use Multiplication Sentences
Multiplication sentences only work when the problem contains an equal number of items in each column or row. For example, if you have a group of items with one item in the first row, two in the second row and three in the fourth row, you must use an addition sentence and add each of the rows together. The addition sentence looks like "1 + 2 + 3 = 6." There is no way to figure that out using a multiplication sentence. In contrast, if you have two items in each row and three items in each column, then you can use a multiplication sentence to express the complete equation. In this example, the sentence would look like "2 x 3 = 6." The number two represents the rows in the array, and the number three represents the number of columns.
Create a Sentence From a Word Problem
Word problems always seem to throw students off, but once students understand how to write a multiplication sentence, word problems should be easier for the students. Provide a word problem, such as "Matt collected a bushel of apples. He has enough apples to place five apples per row six times. How many apples does Matt have? Hurry up and figure out the answer before he eats one." Instruct the students to draw a picture on a grid to help them visualize the problem, and then apply the same concept you use when creating sentences from a grid. In this example, the student should write the multiplication sentence as "5 x 6 = 30."
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