Students will be able to calculate elapsed time and recognize word problems involving elapsed time.
- Introduce the concept of elapsed time to your students. Explain that elapsed time means time that passes. For example, one day has elapsed since the yesterday's class period began.
- Ask students to share some examples of elapsed time. Some guiding questions you can ask are: How much time has elapsed since you woke up? How much time elapses while you eat lunch?
Explicit Instruction/Teacher Modeling(20 minutes)
- On the board, draw a number line (11 ticks) with arrows at both ends. Label each tick with a time: 1:00pm, 1:30pm, 2:00pm...ending with 6:00pm. Let students know that what you drew is a timeline—it shows different times from earliest to latest.
- Show students how to "jump" by hours and minutes. For example, you could go from 2:00pm to 4:00pm by jumping two hours forward. To go one hour and 30 minutes backwards from 5:00pm, you would jump one hour backward to 4:00pm, then 30 minutes backward to 3:30pm.
Guided Practice/Interactive Modeling(20 minutes)
- Distribute a pencil and sheet of lined paper to each student.
- Have students draw their own timelines using yours as a model.
- Give them a start and end time for which to calculate an amount of elapsed time.
- Ask them to make the proper number of hour jumps and note the number beside their timeline. For example, if your start and end time are 1:30pm and 3:00pm, they should make two hour jumps.
- Ask them to make the proper number of minute jumps and note the number beside their timeline. With the current example, they should make 30 minute jumps.
- Have them add the hour and minute jumps they made in order to determine the elapsed time. Ask them to record their answers on their sheets.
- Repeat this exercise with two more sets of start and end times.
Independent Working Time(30 minutes)
- Use the board to display 6 elapsed time word problems. (These can be written down and hidden beforehand to save time.) One problem that you could use is: Morty went on a drive last weekend. He left his house at 1:00pm and arrived at his destination at 4:00pm. How much time elapsed during his drive?
- Give students 20-25 minutes to solve the problems and record their answers.
- Walk around and observe students as they work. Provide assistance when needed.
- Enrichment: Have advanced students try solving some problems using addition and subtraction. Explain that one hour is equal to 60 minutes, so instead of using a timeline, you can add or subtract minutes (up to 60) to find elapsed time. For example, to calculate the elapsed time between 1:30pm and 3:30pm, you would subtract 30 from 30 to get 0 minutes, then 1 from 3 to get 2 hours (or 120 minutes).
- Support: Allow struggling students to use small manipulative clocks as reference tools.
- Over the course of your observation, make notes about common mistakes and what problems students consider difficult.
- Collect the sheets at the end of the exercise. Review them later to further assess student comprehension.
Review and Closing(10 minutes)
- Briefly review the concept of elapsed time.
- Go over the answers to the word problems, pausing occasionally to ask about difficulties that students came across.
- Use the remaining time to answer any questions students have about the lesson content.