Students can practice calculating time intervals with these four multistep word problems designed for third-grade math learners.

Let's solve each problem step by step.

---

Problem 1:

Martin started playing football at 8:20 in the evening. He played for 40 minutes and then took a break. After the break, it was 9:30 pm. How long did Martin take a break for?

#### Step-by-Step Solution:
1. Determine the time Martin finished playing football:
- Martin started playing at 8:20 pm.
- He played for 40 minutes.
- Adding 40 minutes to 8:20 pm:
\[
8:20 + 40 \text{ minutes} = 9:00 \text{ pm}
\]
- So, Martin finished playing football at 9:00 pm.

2. Determine the duration of the break:
- Martin took a break after finishing his playtime.
- The break ended at 9:30 pm.
- The break started at 9:00 pm.
- The duration of the break is:
\[
9:30 \text{ pm} - 9:00 \text{ pm} = 30 \text{ minutes}
\]

#### Final Answer:
\[
\boxed{30 \text{ minutes}}
\]

---

Problem 2:

Chloe started playing piano at 5:40 in the evening. She played for 30 minutes and then watched a TV show. It was 7:15 pm when she finished watching the show. How long did Chloe watch the show for?

#### Step-by-Step Solution:
1. Determine the time Chloe finished playing piano:
- Chloe started playing at 5:40 pm.
- She played for 30 minutes.
- Adding 30 minutes to 5:40 pm:
\[
5:40 + 30 \text{ minutes} = 6:10 \text{ pm}
\]
- So, Chloe finished playing piano at 6:10 pm.

2. Determine the duration of the TV show:
- Chloe started watching the TV show at 6:10 pm.
- She finished watching the show at 7:15 pm.
- The duration of the TV show is:
\[
7:15 \text{ pm} - 6:10 \text{ pm} = 1 \text{ hour and } 5 \text{ minutes}
\]

#### Final Answer:
\[
\boxed{1 \text{ hour and } 5 \text{ minutes}}
\]

---

Problem 3:

Hugo entered a gift store at 10:15 AM. At a quarter to eleven, he left the store and stayed in a coffee shop for 30 minutes. After that, he returned to the gift store and left at half past one. How long did he stay in the gift store in total?

#### Step-by-Step Solution:
1. Determine Hugo's first visit to the gift store:
- Hugo entered the gift store at 10:15 AM.
- He left the gift store at a quarter to eleven (10:45 AM).
- The duration of his first visit is:
\[
10:45 \text{ AM} - 10:15 \text{ AM} = 30 \text{ minutes}
\]

2. Determine Hugo's second visit to the gift store:
- Hugo returned to the gift store after staying in the coffee shop for 30 minutes.
- He left the coffee shop at:
\[
10:45 \text{ AM} + 30 \text{ minutes} = 11:15 \text{ AM}
\]
- He left the gift store at half past one (1:30 PM).
- The duration of his second visit is:
\[
1:30 \text{ PM} - 11:15 \text{ AM} = 2 \text{ hours and } 15 \text{ minutes}
\]

3. Calculate the total time Hugo spent in the gift store:
- First visit: 30 minutes
- Second visit: 2 hours and 15 minutes
- Total time:
\[
30 \text{ minutes} + 2 \text{ hours and } 15 \text{ minutes} = 2 \text{ hours and } 45 \text{ minutes}
\]

#### Final Answer:
\[
\boxed{2 \text{ hours and } 45 \text{ minutes}}
\]

---

Problem 4:

Kevin took 12 minutes to finish checking his e-mails, a quarter to surf the internet, and 15 minutes to finish his lunch. If he started at 9:00 AM, at what time did he finish everything?

#### Step-by-Step Solution:
1. Calculate the total time Kevin spent on all activities:
- Checking e-mails: 12 minutes
- Surfing the internet: a quarter (15 minutes)
- Finishing lunch: 15 minutes
- Total time:
\[
12 \text{ minutes} + 15 \text{ minutes} + 15 \text{ minutes} = 42 \text{ minutes}
\]

2. Determine the finish time:
- Kevin started at 9:00 AM.
- Adding 42 minutes to 9:00 AM:
\[
9:00 \text{ AM} + 42 \text{ minutes} = 9:42 \text{ AM}
\]

#### Final Answer:
\[
\boxed{9:42 \text{ AM}}
\]

---

Summary of Answers:

1. \(\boxed{30 \text{ minutes}}\)
2. \(\boxed{1 \text{ hour and } 5 \text{ minutes}}\)
3. \(\boxed{2 \text{ hours and } 45 \text{ minutes}}\)
4. \(\boxed{9:42 \text{ AM}}\)