7 - Prime factorization - This is an excellent time to talk about "divisibility" and factors
cuisinaire rods. Lesson: Show me 1/2 of an orange rod. (Yellow). Show me 1/2 of a brown rod (purple). Show me 1/2 of a dark green rod (light green). Show me 1/2 of a purple rod (red). Show me 1/2 of a red rod (white). All of these numbers are divisible by 2. Show me 1/3 of a blue rod (green). Show me 1/3 of a dark green rod (red). Show me 1/3 of a light green rod (white). All of these are divisible by 3. Show me 1/4 or a brown rod (red). Show me 1/4 of a purple (white). These are all divisible by 4. Are there any rods that we weren't able to break down into smaller rods (except white)? Black, yellow, light green, red. These are prime numbers. Any number that can't be broken down into smaller parts (except by 1's) are called prime. |
Slide show - I also made a slide show to show divisibility by checking the last digit and by adding the digits. I used a little minion picture and called it "Divisible Me" (Like Despicable Me)
Explanation that numbers that can't be divided by other numbers are prime. |
Number chart practicenumber chart - Have the students circle the primes and cross out the composite numbers on a number chart 1-100. Have students try on their own and do it with them on the white board, crossing out multiples of 2, 3, 5, and 7.
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