# Help! Need a good math lesson on prime & composite numbers.

Discussion in 'Elementary Education Archives' started by ysalazar, Aug 9, 2006.

1. ### ysalazarRookie

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Aug 9, 2006

I'm going to be teaching my first 5th grade math lesson and it's on prime and composite numbers. The other teachers on my grade level are just using the textbook, but I would like to do something a bit more creative and fun.

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Aug 9, 2006

There's a fun activity where you use a hundreds chart and each of the kids has one, too. You give instructions about coloring in all the multiples of 2, 3, 4, etc., and find out which numbers are left blank at the end.

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5. ### AliceaccMultitudinous

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Aug 10, 2006

It's called the Sieve of Erastothenes. I'm sure you can find something if you Google it.

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7. ### AliceaccMultitudinous

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Aug 10, 2006

Oops, sorry, I didn't check!

8. ### novalyneRookie

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Aug 10, 2006

I do an activity to help them visualize prime and composite, using grid paper and construction paper. We just do from 1-20. For each number, they cut each set of factors out using the grid paper. (i.e., 11 gets just 1 row of 11 cut out (1x11), while 12 gets 1 row of 12 (1x12), 2 rows of 6 (2x6), 3 rows of 4 (3x4)). These are glued to the contruction paper and the number and each set of its factors are labeled.

It takes awhile, but when they're done they can actually see that primes have only one set of factors, while composites have more than one. (As a bonus, it's also a great visual to introduce the perfect squares for 4, 9, 16.)

We did the Sieve, also, which was great because my kids couldn't verbalize *why* it worked, which showed me that they were having difficulty understanding the relationship between factors and multiples. So I had to reteach that before they could conceptualize why a multiple of a number was automatically composite!

9. ### KIFCompanion

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Aug 10, 2006

I teach 5th grade math as well and I don't teach the prime and composite lesson from the book. What I do is teach them every day. I have a hundreds pocket charts and each day we flip a number. With that number we put it into a fraction, decimal, and percentage. Then find the factors for the number, then decide if it's prime or composite. The first few days it's harder but by day 10 or so they've got it! Then we reinforce each day for the rest of the year. It covers many standards and it's math warm up each day. We then also do a pattern, stem and leaf plot (mean, median, mode, range), problem of the day, spiral review, then the new lesson. Kids do love it though. At some level, they all find success somewhere in this process.

10. ### MissAmyCompanion

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Aug 10, 2006

KIF I love this idea. Does it take a lot of time to do that every day? You wouldn't have your daily problems on the computer would you?

11. ### KIFCompanion

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Aug 10, 2006

This is also my morning work. Students start working on it as soon as they get into the classroom and I make use of that slow time at the beginning of the day. Overall I spend about an hour and a half on math each day. I don't spend a ton of time on the new lessons since the spiral review includes one problem from each lesson......I move quickly since they'll be sure to see it again.....each day!!!!!! We go step by step, they do, we check, they do, we check.

Basically it's this....

1. calendar math (everyday counts--ish)
2. problem of the day
3. spiral review
4. direct instruction

12. ### MissAmyCompanion

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Aug 10, 2006

KIF- I plan on using the hundreds pocket chart idea... Thanks a lot! We use Saxon math and it spirals so I think I'm good there. Can you give me some examples of your problem of the day? Is that where you have them practice the patterns, stem and leaf plots, mean, median, mode, and range?

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Aug 10, 2006

Do you use the calendar data for the stem and leaf plots?

14. ### KIFCompanion

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Aug 10, 2006

They are simply word problems, but we call it the problem of the day--or the P.o.D!

What is the sum of all the prime numbers between 1 and 13?

A taco costs 99 cents and a drink costs 75 cents. Rico has \$4.00, can he buy 2 tacos and a drink? If so, how much change will he get back. If not, how much more money will he need?

I just googled "math problem of the day" and found this website:

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Aug 10, 2006

16. ### KIFCompanion

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Aug 10, 2006

OOPS! Didn't answer all your questions. The problem of the day is to work on problem solving strategies and I'll use concepts that they've seen in D.I. Patterns is simply a section called "pattern". I have a T-chart on my whiteboard that I use as the stem and leaf. I'll start the year off teaching them how to put a data set onto the graph and find the MMMR, then we switch to pulling off the data. We don't do stem and leaf EVERYDAY, I'll switch around to other types of graph analysis. Problem of the day may or may not be involved with the other sections.

I also have Math Warmup assessments, they are responsibile for the information. a half a sheet of paper with a few questions. I do this since I never really have a unit on graphing, problem solving, or prime/composite.

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Aug 10, 2006

What data do you use for the graphing activities?

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