How to Teach Elapsed Time Word Problems

If you have students working towards understanding elapsed time word problems there are a few strategies you can keep in mind to make the process easier!

All Elapsed Time Word Problems Are Not Created Equally!

When diving into elapsed time word problems, not all problems are the same level of difficulty. An elapsed time problem including hours only is going to be much more simple for your students to solve than a problem to the nearest minute. Use this to your advantage!

Start with simple problems to the nearest hour: Andy woke up at 7:00 am. He spends 2 hours getting ready and then leaves the house. What time did Andy leave the house?

Your students can use this type of problem to get used to using an open number line to solve. When they are presented with a more difficult problem in the future, your students won’t need to problem-solve around the conventions of the problem type but can instead spend their time focusing on the most efficient way to solve the problem.

When your students are confidently using a number line to solve elapsed time word problems involving hours you can then move to problems to the minute: Andy woke up at 7:08 and was ready for school by 7:52. How long did it take Andy to get ready?

Think CRA When Calculating Elapsed Time

When we talk about “thinking CRA” we are considering how a concept can be taught or understood at the concrete, representational and abstract levels.

Elapsed time word problems themselves are at the abstract level. There is no hands-on or visual support for your students. Your students need to be thinking and understanding at an abstract level to solve.

Taking a step backward, you can introduce the tool of an open number line as a helpful representational model for your students. Recording the start and end times as well as the “jumps” along the number line can help to make the concept of elapsed time more visual for your students.

Taking another step backward we can make elapsed time concrete for students by working alongside a model clock. Move the hands on the clock and record (or ask your students to record) those same movements on an open number line. This will help your students to make the connection between time and the visual model.

Try Numberless Word Problems

Numberless word problems are a tool that can help students to focus on the action of a word problem. While an elapsed time word problem may have a missing start time, missing end time or missing elapsed time using a numberless word problem can help your students to follow the action and solve for the unknown.

Let’s try one together!

Start with the context alone: Coco is baking cookies! Her cookies need to bake for a specific amount of time. She puts them into the oven at __:____.

Ask your students what they notice about the story. Who is in the story? What is happening? What do we know about the story? What are we wondering?

Next, introduce your first bit of information: Coco is baking cookies! Her cookies need to bake for a specific amount of time. She puts them into the oven at 2:10.

Ask your students again; What is happening in the story? What new information did we learn? What are we still wondering? How long *might* the cookies go into the oven for? What is a reasonable guess?

Introduce your second bit of information next: Coco is baking cookies! Her cookies need to bake for exactly 13 minutes. She puts them into the oven at 2:10.

Ask your students what new pieces of information they learned in the story. What questions could we ask (or answer!) about this story? Do the cookies bake for a longer or shorter period of time than you anticipated?

Last, present the entire word problem. Coco is baking cookies! Her cookies need to bake for exactly 13 minutes. She puts them into the oven at 2:10. What time should Coco take the cookies out of the oven?

At this point, your students can solve the problem- but don’t stop there! After solving, ask your students if their answer is reasonable and if it matches the story.

Bringing It All Together

Teaching elapsed time? Remember to keep these three tips in mind!

1. All problems are not created equally. Start simple and elaborate as your students confidence grows.
2. Offer hands-on and visual supports alongside abstract elapsed time word problems.
3. Try numberless word problems to help your students focus on the action of these story problems.

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