Multiples and Least Common Multiple (LCM)
Deidre Pendley
Bristol City Schools
5th Grade
Multiples and Least Common Multiple (LCM)
5th Grade
Alignment with State Standards: GLE 0506.2.2 Write natural numbers to 50 as a
product of prime factors and understand that this is unique (apart from order).
SPI 0506.2.2 Write the prime factorization of numbers through 50 using both
exponential and standard notation.
Mathematics Goals: The students will find multiples and the least common multiple
(LCM) of a set of numbers.
Students needs: Students need to be familiar with multiples and common multiples.
This can be through previous lessons or daily practice such as Drops in the Bucket,
ADD’s and Mountain Math.
Materials: workbooks, dry erase boards, dry erase markers, interactive flip charts,
post-it notes
Lesson: Before instruction, I would explain to the students why this lesson is important.
They will need this skill in order to find equivalent fractions and add/subtract fractions
with unlike denominators. I would begin the lesson by orally quizzing the students about
what they already know. We would briefly review multiples and common multiples of
numbers. I would write a number on the board and have the students write the
multiples and circle the common multiples on their dry erase boards in a contrasting
color, holding them up when they are finished. We would complete a few examples
before moving on. I would begin the lesson on least common multiples by showing an
interactive flip chart (www.prometheanplanet.com) on the promethean board. This
begins with a review of definitions for multiple and common multiple and introduces
least common multiple. The students will take turns coming to the board to answer
questions on multiples, common multiples and least common multiples. Those students
at their desks will also participate by answering each question on their dry erase board
and we will check as a class as we go along. I will walk around the room observing
students work and giving help, when needed, during the lesson. At this point, I would
divide the students into groups of two, letting them work together with their dry erase
boards checking each others work. At the end of the lesson I will write a set of numbers
on the board and their “pass to the next class” will be a post-it note with their name,
common multiples and the least common multiple on it. As they are getting ready for the
next class, they will stick their post-it to my bulletin board and those who wrote the
correct answer(s) will be rewarded.
Assessment: I will asses the students through observation, open ended response,
classwork, homework and chapter tests.
Accommodations: Special accommodations could include special seating, extra time
to complete work and modified classwork/homework. Those students can also receive
extra help from RTI teachers and teaching assistants.