Lesson Plan

Grade 6: Number Sense: GCF and LCM (1 of 4)

Introduction to LCM

Lesson Objective

Learners will solve LCM problems using low-order strategies (e.g. number lines, lists, role-play) and demonstrate knowledge of the precursors needed to solve LCM problems employing higher-order strategies.

LCM problems are more engaging than GCF and so I have moved this up in the curriculum. Extra-time may be needed to address deficiencies in the precursors to this section as they are commonly missed in lower grades.

Lesson Outcomes

  • Learners will have the skills needed to identify and solve LCM type-problems using number-lines, lists and/or role-play. We have demonstrated this by solving 1-3 problems in the classroom using collaboration and Math Talk.
  • Learners will have an understanding of the precursors. We have demonstrated this by the Number Sense contest and yesterday’s exit tickets and pre-check homework.
  • Learners will understand the new vocabulary phrase, least common multiple (LCM). We have demonstrated this by developing an index card with an image, a definition, the word ingredients, key-words in problems, and an example of LCM.

Anticipated Learner Misunderstandings

  • Not being able to spot the key words in a problem that signal a need for LCM.
(i.e. least, smallest, first, an event or events happening at the same time, repeating over and over, purchase or get multiple items to have enough, when it will happen again at the same time.)
  • Confusing terms: multiple and factor.
  • Outliers: What to do when there is no common prime factor to start off subsequent division with, why 1 is not an LCM.
  • Missing Precursors: factors, multiples, prime numbers to 100, prime factorization, divisibility rules, subsequent division.

Precursor Checks and Other Preparation Take-aways

  • Math Vocabulary Precheck: Build Marzano Cards for Divisibility Rule, Factor, Multiple, Prime Number, Prime Factor, Least Common Multiple.
  • Factor trees at: mathplayground.com/factortrees.html
  • Prime numbers at: sheppardsoftware.com/mathgames/numbers/fruit_shoot_prime.htm
  • Multiples at: app.nearpod.com/command?puid=0a85c7c98519226e2f1e7e20eea6d191-1&sid=a759c4f8a6ffe1123939de8b4658f832
  • Divisibility rules and divisibility rules practice.

Scheduled Activities

1. Do Now / Calendar Math (5 minutes)

Alternate: Calendar Math Worksheet. Keep notes on the order questions are selected or who gets points.

2. Homework Review (0 minutes)

  • Please have your Marzano cards on your desks. Please finish these by tomorrow.

3. Video Theater (5 minutes)

Many of us problem solvers are like the man in the video asking for help when stuck. What strategies might work better for solving this problem? “Just Do Something.” Sometimes we just need to do something, draw a picture, use a numberline, to get our thinking started.

4. Problem Solving Experience #1 (10 minutes)

Alternate: Lights Flashing or School Bus Stop, Ferris Wheel
What strategy should we use, what might not work, do we have the data we need to solve, what additional information might we need? Let’s try to solve the problem.
What if we add a third animal to the path? How would this change the answer? “A kangaroo has now jumped down the path at 30 feet a hop from where Lisa is still standing. How many feet further down the trail will Lisa next see all three sets of paw prints together along the trail?
After about 5 minutes, I will have a group share their findings.

5. Problem Experience #2 (5 minutes) (if there is time remaining)

(i.e. least, smallest, first, an event or events happening at the same time, repeating over and over, purchase or get multiple items to have enough, when it will happen again at the same time.)

6. Close-up (5 minutes)

  • Write down homework.
  • Vocabulary - Develop (or revise) your Mazano card for LCM. Include a definition, a DIY guide, a symbol or picture, an antonym. We look for keywords in a problem that call us to use the LCM strategy. We practice looking for these keywords in problems.
  • Voice of the Student - How was today’s class -- eek, meh, loved it? What worked, what didn’t work?
  • Exit-Tickets (none for this session)
(Note: Through using a problem-solving interview approach, reviewing my notes will show where there are learner misunderstandings for this class.)


  • In your notebook, write down the keywords that you find for the six LCM problems provided. Finish one problem from this list that you have not completed in class.
  • Complete the Marzano Card (blank) (with instructions) for LCM, if not completed when assigned yesterday. Print and bring to class today.
  • Continue precursor practice. Factor Tree, Prime Number, Divisibility Rules, “Take the Prime Number Challenge” Packet in binder.