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    • ▾4th grade
      • ▸Place value of whole numbers
        • •Place value of multi-digit whole numbers
        • •Adding and subtracting multi-digit numbers
        • •Multiply and divide by 10
        • •Represent a number using base ten blocks, units, tens, and hundreds
        • •Convert between written forms of numbers
        • •Round whole numbers
        • •Estimating sums and differences by rounding
        • •Estimating products by rounding
      • ▸Multiplication and division
        • •Multiplying one-digit numbers by 10, 100, and 1000
        • •Multiplying one-digit numbers by multiples of 10, 100, and 1000
        • •Multiplying 10s
        • •Multiplication
        • •Quotients and remainders
        • •Pattern in the units digit of multiples
        • •Solve multiplication and division word problems
        • •Multi-step word problems
      • ▾Factors, multiples, and patterns
        • •Factors and multiples
        • •Divisibility tests
        • •Prime and composite numbers
        • •Number patterns
      • ▸Equivalent fractions and comparing fractions
        • •Equivalent fractions
        • •37 trick
        • •Compare fractions with unlike numerators, denominators, or both
      • ▸Fraction arithmetic
        • •Round fractions
        • •Add and subtract fractions with like denominators
        • •Add fractions with denominators of 10 or 100
        • •Multiply fractions by whole numbers
      • ▸Understand decimals
        • •Represent decimal numbers using base ten blocks
        • •Compare decimals to hundredths
      • ▸Geometry
        • •Intro to parallel and perpendicular lines
        • •Lines of symmetry
        • •Rotational symmetry
        • •Intro to angles
        • •Measuring and drawing angles
        • •Coterminal angles
        • •Naming angles
        • •Adjacent angles and the additive property of angles
      • ▸Units of measurement
        • •Converting larger units of volume to smaller ones
        • •Converting larger units of length to smaller ones
        • •Converting larger units of time to smaller ones
        • •Word problems involving measures
     › 4th grade › Factors, multiples, and patterns

    Prime and composite numbers

    Students will learn how to determine whether a whole number is prime, composite, or neither. Before learning this, your students must be comfortable performing divisibility tests.

    Watch these Khan Academy videos:

    • Prime numbers
    • Recognizing prime and composite numbers

    Do these Khan Academy exercises:

    • Identify prime numbers
    • Identify composite numbers
    • Identify prime and composite numbers

    Next, students will investigate several number spirals. Start by exploring the spirals seen here. I think this would be done best by giving your students unshaded grids on sheets of paper or via software, then asking them to shade the square numbers, or shade the multiples of four, etc. After investigating various properties of these spirals, show them this video or relay the ideas therein.

    Make LaTeX sheets for the number spirals, so teachers can print them. Later, develop software so that shading the spirals is as easy as clicking the mouse.

    Next, give your students these challenges:

    • The Vegetable Garden by NRICH
    • Even and Odd by NRICH

    Conclude by leading this investigation:

    Prime Cubes by JRMF

    4.OA.B.4: 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 a multiple of a given one-digit number. Determine whether a given whole number in the range 1-100 is prime or composite.

    Additional lessons and practice problems