ALEX Lesson Plan


Finding Prime

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  This lesson provided by:  
Author:Jessica Jeffers
System: Enterprise City
School: Hillcrest Elementary School
The event this resource created for:GEMS
  General Lesson Information  
Lesson Plan ID: 23843


Finding Prime


Students will work in groups to discover the meaning of prime. Tiles will be used to build rectangular arrays for a given number.
This lesson plan was created as a result of the Girls Engaged in Math and Science, GEMS Project funded by the Malone Family Foundation.

 Associated Standards and Objectives 
Content Standard(s):
MA2015 (2016)
Grade: 6
12 ) Write and evaluate numerical expressions involving whole-number exponents. [6-EE1]

Local/National Standards:

NCTM: Algebra - Use factors, multiples, prime factorization, and relatively prime numbers to solve problems.

Primary Learning Objective(s):

Students will be able to find and identify prime numbers.

Additional Learning Objective(s):

Students will build rectangular arrays for a given number. Students will use factor pairs to help construct their arrays. Students will draw diagrams of all possible arrays for a given number.

 Preparation Information 

Total Duration:

31 to 60 Minutes

Materials and Resources:

Materials for the lesson include graph paper and colored tiles.

Technology Resources Needed:

LCD (optional) This is a great site for a follow up lesson or as a demonstration. AskDr.Math


Students should have an understanding of multiplication and its properties.

1.)Place students into groups of two.

2.)Ask the pairs to build as many different rectangles as possible using 12 tiles.

3.)Walk around answering questions that arise. Some students will try building rectangles using twelve tiles as an outside perimeter. Be sure to explain that the rectangular arrays must have no holes in the middle.

4.)Have different groups share their findings. (3x4, 6x2, and 12x1)

5.)Have students draw their rectangles on graph paper and list their factor pairs for each rectangular array.

6.)Give students at least two more composite numbers to build, share and draw.

7.)Give students the number 7 and ask them to build as many possible rectangles using only 7 tiles.

8.)Discuss how their is only one rectangle that can be built using 7 tiles (7x1 or 1x7).

9.)Give students another prime number and ask them to build and graph as many rectangles as possible.

10.)When students realize that once again their is only one rectangle possible share with them that this is because these are special numbers we call prime numbers.

11.)Display a hundreds chart on an Interactive White Board (see link). Allow groups to come to the front and shade the prime numbers they found and share their strategy for finding the primes.
(Hundreds Chart)
This site offers lessons using the hundreds chart and also a blank template of the hundreds chart.


Assessment Strategies

Wrap up the lesson by stating that today they have discovered the meaning of prime. Ask students to work with their partner to write down what they think is the definition of a prime number. Have students look up the meaning of prime in the dictionary and compare it with their definition as well as their partner's definition. The teacher may use summative evaluation by listening to each groups discussion on their discoveries about prime numbers.


Students already familiar with the concept of prime can be given the challenge of finding all prime numbers between 1 and 100. Counting cards with the numbers 1-100 on them and colored chips can be used to to this. The students or teacher may use the link listed in the Technology Resources category for lesson introduction or follow-up. Also, you can extend this lesson by opening the discussion about Pascal's Triangle and use this link to introduce it to the students. This activity Pascal's Petals leads into the discovery of prime factorization.


Students having difficulty achieving the objective can be allowed the use of tiles during future lessons and test. Being allowed the use of tiles to build rectangles gives the students extra support in order to be successful. Students with mastery of their multiplication facts will be able to master the objective using that knowledge as a guide for finding prime numbers. Students without mastery of their facts will find the use of tiles helpful in future exercises.

View the Special Education resources for instructional guidance in providing modifications and adaptations for students with significant cognitive disabilities who qualify for the Alabama Alternate Assessment.