Download the Lessonotes Mobile Liberia app for faster lesson access on Android and iPhone.
Subject: Mathematics
Semester: 1
Period: 1
Week: 2
School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 2
Date: Week 2
Lesson Duration: 45 minutes
Week & Period: Week 2, Period 1
Topic: Disjoint Sets and Addition Using Union of Sets
Sub-topic: Union of disjoint sets
Learning Objectives
By the end of the lesson, students should be able to:
• Understand disjoint sets
• Add numbers using union of disjoint sets
• Apply set union in real life
Previous Knowledge
Students already know how to form and compare sets.
Instructional Materials
Mathematics textbook for Grade 2
Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks: “If we have a set of boys and a set of girls in this class, can one person be in both sets?” Learners respond: “No.” Teacher introduces disjoint sets.
B – Building Knowledge (Main Lesson Body)
Time: 25–30 minutes
Disjoint sets are sets that do not share any elements. Example: Set A = {👦, 👦, 👦} (boys), Set B = {👧, 👧, 👧, 👧} (girls). These two sets are disjoint because no element is in both sets. The union of two sets (A ∪ B) means joining all elements of both sets together. The total number of elements in A ∪ B is found by adding the number in A and the number in B. Example: If Set A has 3 boys and Set B has 4 girls, then A ∪ B = 3 + 4 = 7 learners.
Learners’ Activities (Expanded):
Learners form groups of boys and girls in class and count them. Learners draw Venn diagrams of disjoint sets and show the union. Learners solve examples: If Set A = {2 pencils}, Set B = {3 books}, find A ∪ B.
Assessment Checks:
What are disjoint sets? What does union of sets mean? If Set A has 5 elements and Set B has 2 elements, what is A ∪ B?
Notes (Expanded & Detailed):
Disjoint sets have no common elements. The union of disjoint sets means joining all elements together. Addition of numbers is linked to the union of sets.
C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Disjoint sets do not share elements. Union of sets means combining. We add the number of elements in both sets to get the total.
Evaluation Method (Expanded):
Exit slip/quiz: Draw two disjoint sets and show their union. Teacher will collect slips and provide oral feedback.
Assignment (Expanded):
At home, form disjoint sets of objects (cups and spoons). Count and add the total elements.
Follow-up Activity:
Practice Venn diagrams of disjoint sets on the board.
Differentiation / Inclusive Strategies
Use pictures and flashcards for visual learners. Pair learners to practice group work.
Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☑ Medium ☑ Low