Liberia - Grade 4 - Mathematics - Estimating & Telling Time

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Subject: Mathematics

Semester: 2

Period: 5

Week: 25

School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 4
Date: Week 25
Lesson Duration: 45 minutes
Week & Period: Week 25, Period 5
Topic: Estimating & Telling Time
Sub-topic: Estimating short and long activities; Finding elapsed time

Learning Objectives
By the end of the lesson, students should be able to:

Distinguish between short and long activities.
Estimate how long common activities take.
Calculate elapsed time using toy clocks, timelines, and addition or subtraction of hours and minutes.

Previous Knowledge
Students already know the names of days of the week, months of the year, and how to read numbers on a clock.

Instructional Materials
Mathematics textbook for Grade 4, toy clocks, chart of daily activities, timelines, chalkboard.

Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks students: “Which takes longer: brushing your teeth or cooking rice? Which is shorter: eating breakfast or going to school?” Students respond by raising hands. Teacher writes answers on the board.

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes
Topic: Estimating and Finding Elapsed Time

🔍 Key Definitions (Expanded)

Estimating Time
Estimating time means making a reasonable guess about how long an activity will take without using a clock or stopwatch. This helps us plan our day and understand the concept of time even when we don’t have a precise time-measuring tool.
- Important Point: Estimating is not exact; it’s close to the actual time.
- Why It Matters: Helps with daily planning, time management, and understanding duration.
Elapsed Time
Elapsed time is the actual amount of time that passes between the start and end of an activity or event.
- Formula (basic):
  Elapsed Time = End Time – Start Time
- Can be measured in: minutes, hours, or a combination of both.

🧠 Examples of Estimating Time (Expanded)

Activity	Estimated Time
Brushing teeth	About 5 minutes
Eating breakfast	About 15–20 minutes
Walking to school	About 10–30 minutes
Cooking rice	About 30–40 minutes
Watching a movie	About 2 hours
Attending school	About 6 hours (8:00–2:00)
Becoming a doctor	About 10–12 years
Taking a bath	About 10–15 minutes
Doing homework	About 30–60 minutes
Playing outside	About 1 hour

⏰ Finding Elapsed Time (Expanded with Multiple Methods)

Method 1: Using Toy Clocks

Move the hands to the start time, then move them forward to the end time.
Count the hours and minutes passed.

🧩 Example:
Start: 2:00 PM
End: 3:30 PM
→ Move the hour hand from 2 to 3 (1 hour), then the minute hand from 00 to 30 (30 minutes).
✅ Elapsed Time = 1 hour 30 minutes

Method 2: Using Timelines

Draw a number line or a timeline.
Mark the start time and end time.
Count the hours and minutes passed using intervals.

🧩 Example:
Start: 1:45 PM
End: 4:00 PM

Time	Interval
1:45 → 2:00	15 min
2:00 → 4:00	2 hr

✅ Elapsed Time = 2 hours 15 minutes

Method 3: Using Subtraction

Convert times to hours and minutes (use 24-hour format if needed).
Subtract the start time from the end time.

🧩 Example:
End: 3:30 PM
Start: 2:00 PM
→ 3:30 – 2:00 = ✅ 1 hour 30 minutes

🧩 Example:
End: 1:15 PM
Start: 11:50 AM
→ Convert to minutes:

1:15 = 75 minutes past 12
11:50 = 710 minutes since midnight
1:15 = 13 × 60 + 15 = 795
795 – 710 = 85 minutes
✅ Elapsed Time = 1 hour 25 minutes

🧍‍♀️ Learners’ Activities (Expanded)

Act It Out – Estimating Time Game
- Students are given a list of common activities (e.g., tying shoes, writing a sentence, walking across the room).
- They estimate how long each task will take, then perform the task while a classmate uses a stopwatch or timer.
- Compare estimates with actual times and discuss differences.
Group Clock Work – Toy Clock Exploration
- In small groups, students are given start and end times (e.g., 9:15 AM to 10:45 AM).
- They set start and end times on toy clocks and count forward in steps of 5 minutes or 15 minutes.
- Each group presents how they calculated elapsed time.
Timeline Challenge
- Students draw and label their own timelines for different real-life scenarios (e.g., time between lunch and home time).
- Add colorful arrows to show the intervals passed.
Time Detective Word Problems
- Solve mystery problems like:
  “Ali started his homework at 4:10 PM and finished at 5:35 PM. How long did he work?”

✅ Assessment Checks (Expanded)

Ask individual or group questions to assess understanding:

Quick Check:
If school starts at 8:00 AM and ends at 2:30 PM, how many hours and minutes is that?
- Expected Answer: 6 hours 30 minutes
Estimation Check:
Estimate how long it takes to brush your hair. How would you check if you're correct?
Clock Reading Check:
Show toy clock with 10:00 → 11:15
- Ask: What is the elapsed time?
- Expected: 1 hour 15 minutes
Timeline Problem:
Draw a timeline for this: You play outside from 3:40 PM to 5:10 PM. How long did you play?
Subtraction Problem:
You start reading a book at 7:45 PM and finish at 9:05 PM. Use subtraction to find elapsed time.

📝 Teacher Notes (Expanded & Detailed)

Emphasize the difference between estimation and exact calculation:

Estimation is a skill used to make a smart guess.
Elapsed time can be measured exactly using clocks, timelines, or subtraction.

Reinforce vocabulary:

“Start Time”
“End Time”
“Elapsed Time”
“Estimate”

Encourage mental math strategies and visual aids.
Scaffold the methods:

Begin with hands-on activities → then timelines → then subtraction method.

Be patient with clock reading – many students confuse hour and minute hands.

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Estimation is a guess of time; elapsed time is the exact time passed.

Evaluation Method (Expanded)
Exit slip/quiz: Students write how long brushing teeth, cooking rice, and school day take. Teacher will collect slips and provide oral feedback.

Assignment (Expanded)
Write down five daily activities at home, estimate the time each takes, and check with an adult using a clock.

Follow-up Activity
Students will time themselves while doing homework and compare to their estimate.

Differentiation / Inclusive Strategies
Pair weaker students with stronger ones for clock activities. Use visual aids and timelines for learners with difficulty in mental calculations.

Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☑ Medium ☑ Low