Multiplication in Fourth Grade
While students are expected to come to fourth grade with a reasonable grasp of the basic facts, this unit will review them and give students another chance to memorize the basic facts from 0 x 0 to 10 x 10. Students will use this understanding to identify factors and multiples of numbers under 100.
This is the first major unit of fourth grade. By the end of the year, students will be expected to multiply larger numbers up to a one-digit number by a four-number or a two-digit number times a two-digit number.
It is very important to note that students are not going to be expected to only rely on the same memorized steps we are all learned to multiply. It will also not be enough for students to know only one way to solve a problem. They will often be asked to show two ways to answer a question, or to recognize how someone else has solved it. This requires deep understanding. Here are some of the strategies they will have to use. We have included links to videos explaining and demonstrating each of these strategies.
Modeling with Manipulatives
Distributive Property (also called "break-apart" or "decomposing")
Area Model
Partial Products
This is the first major unit of fourth grade. By the end of the year, students will be expected to multiply larger numbers up to a one-digit number by a four-number or a two-digit number times a two-digit number.
It is very important to note that students are not going to be expected to only rely on the same memorized steps we are all learned to multiply. It will also not be enough for students to know only one way to solve a problem. They will often be asked to show two ways to answer a question, or to recognize how someone else has solved it. This requires deep understanding. Here are some of the strategies they will have to use. We have included links to videos explaining and demonstrating each of these strategies.
Modeling with Manipulatives
Distributive Property (also called "break-apart" or "decomposing")
Area Model
Partial Products
Click on the links below to watch videos showing how to apply some multiplication strategies:
Add Distributive Property Add Partial Products |
Multiplication Vocabulary
For more vocabulary help, try the excellent math glossary at Math Is Fun Factor - The whole numbers that are multiplied to get a product. They are often listed in pairs. For example, in the problem 3 x 2 = 6, 3 and 2 are the factors and 6 is the product. We often ask students to list all possible factors of a number. In that case, all the possible factors of 6 are 1, 2, 3, 6 because 1 x 6 = 6 and 2 x 3 = 6 Product - The answer to a multiplication problem. In the problem 3 x 4 = 12, 12 is the product. Multiple - The product of any two whole numbers. We often ask students to list five or six multiples of a number, or determine if a number is a multiple of another number. Example: list 4 multiples of 4 (4, 8, 12, 16) OR is 20 a multiple of 4? (yes because 4 x 5 = 20) Distributive Property - breaking apart problems in two simpler problems. Example: (3 x 21) = (3 x 20) + (3 x 1) note: students are not necessarily expected to correctly use parentheses and the order of operations. It is more appropriate to expect a student to verbalize that they can solve 23 x 4 by multiplying 20 x 4 and 3 x 4 and adding together the answers. Skip counting - repeatedly adding the same number over and over (example, skip counting by 5 sounds like this: 5, 10, 15, 20, 25, 30, etc…) we can solve multiplication problem by using skip counting. We can use number lines or hundred charts to keep track as we skip count. |
Array - A set of objects or pictures in equal rows and equal columns. We use them to represent a multiplication problem.
Area Model - Pictorial model representing multiplication through the formula for area, usually represented as rectangles, often built with base ten blocks. Prime Numbers - A whole number greater than 1 with exactly two factors, 1 and itself (example - 11 is prime because 11 x 1 = 11 but there is no other multiplication equation using whole numbers that has 11 as an answer) Composite Numbers - A whole number that has more than two whole-number factors (example: 15 is a composite number because 1 x 15 = 15 and 3 x 5 = 15) Divisible - a number is divisible by another number if it can be divided evenly with no remainder by that number. (example: 20 is divisible by 10 because 20 ÷ 10 = 2 but 20 is not divisible by 3 because 20 ÷ 3 = 6 R 2) |
Base ten blocks (flats, rods, and units) - blocks used to represent ones, tens, hundreds and thousands. We call these units, rods, flats and blocks. We expect students may sometimes solve problems using pictures of these blocks.