### Unit 2

 In this unit, the students will build on their work with multiplication and division from grade 3.  In the first part of the unit, they will extend their understanding of the base-ten system by recognizing that the value of each place is ten times the value of the place to the immediate right. Students will develop understanding of multiples and factors, applying their understanding of multiplication from grade 3.  This understanding lays a strong foundation for generalizing strategies learned in previous grades to develop, discuss, and use efficient, accurate, and generalizable computational strategies involving multi-digit numbers.  These concepts and the terms “prime” and “composite” are new to grade 4, so they are introduced early in the year to give students ample time to develop and apply this understanding.  Students will focus on building conceptual understanding of multiplication of larger numbers and division with remainders.  Area of rectangles provides a context for further developing this understanding. Students need to: Recognize that in a multi-digit whole number, a digit in one place represents ten times what it represents in the place to its right.  For example, recognize that 700 ÷70 = 10 by applying concepts of place value and division. Find all factor pairs for a whole number in the range 1-100.  Recognize that a whole number is a multiple of each of its factors.  Determine whether a given whole number in the range 1-100 is prime or composite. Generate a number pattern that follows a given rule.  Solve word problems posed with whole numbers, including problems in which remainders must be interpreted.  Represent these problems using equations with a letter standing for the unknown quantity.  Assess the reasonableness of answers using mental computation and estimation strategies including rounding. Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations.  Find whole-number quotients and remainders with up to four-digit dividends and one-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division.  Apply the area formula for rectangles in real-world and mathematical problems. Carroll County Public Schools Video Support Multiplication of 2-Digit Numbers Multiplication of 2-Digit Numbers Ways Parents Can Help   Encourage your child to regularly practice basic multiplication and division facts. The Internet has many free fact practice sites available. Extend multiplication fact practice to include multiples of 10 and 100. Have your child try to solve them mentally! Examples: 20 x4 = 80; 7 x 300 = 2,100   Look for opportunities for your child to apply multiplication and division to solve real-life problems. Discuss how to interpret the "leftover," or remaining, amount in a division situation. For example: If party plates come in packages of 8, and you are having 75 people for a party, how many packages of plates would you need to buy? Would there be any plates leftover? Some Support Sites