Lucky Luggage Tags: Elapsed Time to the Hour
Lesson 3 of 11
Objective: SWBAT calculate elapsed time to the closest half hour and hour using a number line.
Introduce/review the key vocabulary term elapsed.
This can be done while discussing the homework from last night by inserting the word elapsed into the conversation.
"I see that you ate dinner at 5 p.m. and at 6 p.m. you were reading. An hour elapsed between the time you were eating dinner and the time that you were reading."
Depending on the background experience of your students, they can either think about and share with partners what they know about time zone changes and/or you can explain using a globe or a wall map.
Tell them that today we will explore elapsed time by rounding arrival and departure times from airports to the nearest hour, adding or subtracting hours from the departure time to account for time zone changes, and finally determining the total flight time (elapsed time).
If needed, model sentences which use the words arrive and depart in a familiar context, have them create oral sentences for each of the words, and then talk about how verbs can be nouns when they represent the concept of the action, not the action itself. (Arrival is the idea of coming to a place, and so on).
I also quickly review rounding to closest hour .
The review of time to the hour is set within the context of a much more complicated task to provide students with diverse entry points.
Some students will be thinking about time to the minute (3rd grade standard) or the closest 5 minute (2nd grade standard) as they round the arrival and departure times to the closest hour. Other students, needing more scaffolding, will benefit from the review of time to the hour.
All students will benefit from repeatedly counting across the twelve, this is a consistent trouble spot with elementary students because time is an odd, non tens-based system for a concept that is already an abstraction.
Also of benefit to struggling, on-level, and above level students is the practice with rounding to the closest hour with 30 (minutes) as a halfway point.
I demonstrate how to set up a simple time number line (for this lesson I only demarcated the quarter hour or 5 minute intervals because the focus is on the hour). Then I give students 5-10 sample problems such as:
(Below level but okay for a warm-up!)
If it is 2 p.m. now, what time will it be 5 hours from now?
If it is 5 p.m. now, what time will it be 6 hours from now?
If it is 1 p.m., what time was it an hour ago?
If it is 9 a.m., what time was it 3 hours ago?
(crossing the 12)
If it is 9 a.m., what time will it be in 8 hours?
If it is 1 p.m., what time was it 6 hours ago?
If it is 8 p.m., what time will it be 5 hours from now?
If it is 6 a.m., what time was it 7 hours ago.
(counting on w/hours, time to the 5 minute, crossing the 12)
If it is 12:05 p.m. now, what time will it be in 4 hours?
If it is 12:05 p.m. now, what time was it 4 hours ago?
If it is 9:35 p.m. now, what time will it be in 3 hours?
If it is 9:35 p.m., what time was it 3 hours ago?
The idea of time zones is complex and hard to imagine as we feel very stationary as we go about our day-to-day business on our rotating and revolving planet. This video explains rotation, revolution, sidereal days and solar days and also provides excellent visuals to support each of the concepts. If you start at 3:20, that is where the discussion of days and time zones is emphasized. If students watch this it will move them further along in their understanding of how one part of the earth can experience sunrise at the same time that another region of the earth experiences sunset, or darkness. It is also a good model for moving them away from the idea that the time zone is tied to a country rather than that country's specific coordinates on the planet.
This practice with elapsed time also provides diverse entry points for students. At the most basic level, it helps students practice adding on or subtracting hours from a given time. At a more sophisticated level, it helps them work with their understanding of time to the minute by rounding arrival and departure times to the closest hour.
The powerpoint with a step-by-step process, with visualizations, helps students grapple with the complexity of working with time, in a real-world manner (e.g., time zones and air travel) as they solve multiple-step word problems.
This real-time view of the Earth is worth pulling up and opening in a second window as you go through the activity. It will not match the times in the lesson but it will demonstrate to students how different parts of the earth are experiencing different parts of the day simultaneously.
This simple independent practice with finding elapsed time for direct flights will demonstrate how well students understood, and were able to apply, the concept of elapsed time as it was presented in today's lesson.
Students drew open number lines and used the departure and arrival times (with one of them adjusted for time zone changes) as the start and end points.
To close, I ask students to write down one thing they learned or one idea they reviewed using the Lucky Luggage exit ticket, because their ability to express what we did in the lesson is very informative. I also ask students to rank how they are feeling. That way I can be sure to get to the children who are less confident or confused, especially since those are the students who may not be able to articulate or show their confusion in the written response.
For fun, I make up luggage tags for the children using the real airport codes and throughout the week I ask them to find the locations we visited in this lesson on a map and if they are able to do so/can locate it on an individual or classroom map, they earn a luggage tag. The tags are hole punched on cardstock and I give them a string to hang them on.