Activities That Last Longer Than 20 Minutes

Learn to measure, compare, and analyze extended duration activities for 3rd grade math students, focusing on time periods longer than 20 minutes.

Time Measurement Concepts
Key Definitions:

Duration: The amount of time something takes

Elapsed Time: Time that passes from start to finish

20 Minutes: A quarter of an hour (20/60 = 1/3 hour)

Extended Activity: Something that lasts longer than 20 minutes

Time Unit Conversions
1 Minute:
60 seconds
20 Minutes:
1,200 seconds
30 Minutes:
½ hour
60 Minutes:
1 hour
Time Measurement Tools:

• Clocks: Analog and digital timepieces

• Stopwatches: For precise timing

• Timers: To track duration

• Calendars: For longer periods

Time Memory Aid:

"60 seconds = 1 minute"

"60 minutes = 1 hour"

"20 minutes = 1/3 hour"

Remember: Big to small = multiply, small to big = divide!

Second (s)
1 s
Smallest unit
Minute (min)
60 s
Medium unit
Hour (hr)
60 min
Large unit
Activities That Last Longer Than 20 Minutes
0 min
20 min
30 min
45 min
60 min
1 Reading Time
Problem 1
Emma reads for 35 minutes. Is this longer than 20 minutes? How much longer?
Solution Process:

Given: Emma reads for 35 minutes

Compare: 35 minutes vs 20 minutes

Calculate: 35 - 20 = 15 minutes longer

35 min
>
20 min
Emma's reading time: 35 minutes (longer than 20)
Emma's time
35 min
Compare to
20 min
Difference
15 min
Step 1: Compare the times

35 minutes vs 20 minutes

Step 2: Calculate the difference

35 - 20 = 15 minutes

Yes, 35 minutes is 15 minutes longer than 20 minutes
2 Exercise Time
Problem 2
Jake runs for 45 minutes. How many hours and minutes is this? Is it longer than 20 minutes?
Solution Process:

Convert: 45 minutes to hours and minutes

Compare: 45 minutes vs 20 minutes

Result: 45 minutes = 0 hours 45 minutes

45 min
>
20 min
Jake's running time: 45 minutes (longer than 20)
Total minutes
45 min
Hours
0 hr
Minutes
45 min
Step 1: Determine if it's longer

45 minutes > 20 minutes, so yes

Step 2: Convert to hours and minutes

45 minutes = 0 hours and 45 minutes

45 minutes = 0 hr 45 min (longer than 20 minutes)
3 Movie Time
Problem 3
A movie lasts for 1 hour and 15 minutes. How many total minutes is this? Is it longer than 20 minutes?
Solution Process:

Convert: 1 hour 15 minutes to total minutes

Compare: Total minutes vs 20 minutes

Calculate: (1 × 60) + 15 = 75 minutes

1 hr 15 min
>
20 min
Movie time: 75 minutes (much longer than 20)
Hours to minutes
1 × 60 = 60
Add minutes
+ 15
Total
75 min
Step 1: Convert hours to minutes

1 hour = 60 minutes

Step 2: Add the remaining minutes

60 + 15 = 75 minutes

Step 3: Compare to 20 minutes

75 > 20, so it's longer

1 hr 15 min = 75 minutes (longer than 20 minutes)
Time Comparison Methods
Comparison Techniques
Method 1:
Direct comparison
Method 2:
Convert to same units
Method 3:
Calculate differences
Method 4:
Use timeline visualization
Step-by-Step Process:
  1. Identify: What times are being compared
  2. Convert: Put both times in same units (minutes)
  3. Compare: Use greater than, less than, or equal
  4. Calculate: Find the difference if needed
  5. Verify: Check that answer makes sense
Common Errors to Avoid:

• Mixing different time units without converting

• Forgetting that 1 hour = 60 minutes

• Making arithmetic mistakes with time calculations

• Not considering whether the activity is actually longer than 20 minutes

Additional Practice:

Problem A: Is 25 minutes longer than 20 minutes?

Problem B: Is 1 hour longer than 20 minutes?

Problem C: Which is longer: 30 minutes or 25 minutes?

Time Comparison Strategy:

• Always convert to the same unit before comparing

• Remember: 20 minutes = 1/3 hour

• Use visual aids like timelines for complex comparisons

Real-World Applications:

• Planning daily schedules

• Managing homework time

• Organizing play activities

• Understanding TV/movie durations

Extended Activity Examples
Extended Activity Duration > 20 minutes
Duration Requirement
Common Activities:

School Subjects: Math class (45 min), Science lab (50 min), Art period (40 min)

Household Tasks: Cleaning room (30 min), Cooking dinner (60 min), Bath time (25 min)

Recreation: Soccer game (60 min), Piano practice (30 min), Swimming lesson (45 min)

Transportation: Car ride to school (25 min), Bus commute (35 min), Train trip (45 min)

Duration Categories
Short (≤20 min):
Brushing teeth, snack time
Medium (20-60 min):
Reading, exercise, chores
Long (>60 min):
Movies, sports events, projects
Activity Duration Minutes Longer than 20?
Math Homework 30 minutes 30 Yes
TV Show 30 minutes 30 Yes
Playing Outside 45 minutes 45 Yes
Family Dinner 40 minutes 40 Yes
Tip 1: Use a timer to track real activity durations.
Tip 2: Practice estimating before measuring actual time.
Tip 3: Create personal schedules with time estimates.

Questions & Answers

Question: How can I tell if an activity is longer than 20 minutes without using a clock?

Answer: You can estimate by comparing to familiar activities! For example:

  • Brushing teeth: about 2-3 minutes (much shorter than 20)
  • Eating breakfast: about 15-20 minutes (about 20 minutes)
  • Watching a cartoon episode: about 20-30 minutes (around or longer than 20)
  • Walking to school: varies, but often 15-30 minutes

If an activity feels like it takes longer than eating breakfast, it's probably longer than 20 minutes!

Question: How can I help my child practice measuring activities that last longer than 20 minutes?

Answer: Try these hands-on activities:

  1. Time household tasks: Cooking, cleaning, gardening
  2. Track recreation: Playing games, reading, drawing
  3. Use timers: Set for different intervals and see how many activities fit
  4. Create schedules: Plan activities and predict durations

Make it fun by turning time estimation into a game!

Question: Why do we need to know if activities are longer than 20 minutes? Why not 15 or 25 minutes?

Answer: 20 minutes is a good benchmark because:

  • It's a significant portion of an hour (1/3 of an hour)
  • Many activities naturally fall into this duration range
  • It's long enough to accomplish meaningful tasks
  • It helps distinguish between quick tasks and extended activities

Teachers and parents often use 20-minute intervals for planning and scheduling!