As Time Goes By
Standard Met: CCSS.Math.Content.3.MD.A.1
What You Need: Chart paper, markers, writing or grid paper
What to Do: Education blogger Tammy DeShaw, from Middleville, Michigan, struggled with understanding elapsed time as a child, so she developed strategies and practice activities to help her third graders master the skill. One such strategy she uses is called Mountains, Hills, and Rocks.
“Math is like a road map. It doesn’t matter which route a student takes as long as he or she arrives,” says DeShaw, who blogs at The Owl Teacher.
DeShaw shows time pass with a time line. A mountain represents an hour, a hill between five and 30 minutes, and a rock one minute. Students chunk segments of time to make them easier to conceptualize and add together. To show the time elapsed between 7:30 and 9:02, for example, draw a mountain (one hour) to go from 7:30 to 8:30 and a hill (30 minutes) to go from 8:30 to 9:00. Add two rocks, each one representing a minute. Then, show students how this adds up: 1 hour + 30 minutes + 1 minute + 1 minute = 1 hour and 32 minutes.
Students can practice this method by creating their own time lines (and even their own icons) to show what happens during their day. For instance, a student may draw time lines showing that he eats breakfast between 7:55 and 8:24 (two hills and four rocks), travels to school between 8:28 and 9:00 (two rocks and a hill), and so on.
Standard Met: CCSS.Math.Content.2.MD.C.7
What You Need: Masking tape, student mini-clocks (use template, if needed)
What to Do: Deana Kahlenberg, a speech-language pathologist and former third-grade teacher, finds that “turning learning into a game” helps students grasp tricky concepts involving time. Kahlenberg, who blogs at Primary Punch and is from Hope Mills, North Carolina, modifies the classic “Red Light, Green Light” game to help kids practice time-telling strategies.
Prepare the activity by laying down two parallel lines of tape. The lines should be 15–20 feet apart, if possible. If you’re short on space, take the activity outside or have students take baby steps. Briefly review time-telling concepts before beginning the game.
Then, hand out a mini-clock to each student (consider printing and making a class set of mini-clocks if you don’t have a set), and have students stand side by side on one of the lines. Kahlenberg starts by calling out a time. For beginners, she suggests calling out times by the hour or half hour. For more advanced learners, add in a mix of times and terminology like half past, a quarter to, or times to the minute. Students mark the time on their clocks and hold them up. Those with the correct time get a “green light” and take a step forward toward the other line. Students who show an incorrect time get a “red light” and stay in place.
Continue calling out times and checking for understanding. Scaffold and support as needed. The first player to cross the opposite line wins.
For an extra challenge, test students’ comfort with elapsed time. For example, have students display a time like 4:45. Then, ask them to show the time 17 minutes later.
Time to Roll the Dice
Standard Met: CCSS.Math.Content.2.MD.C.7
What You Need: Mini-whiteboards, dry-erase markers, mini-clocks, clock dice (or use multiple 6- and 12-sided dice), blank clockfaces handout (you can find free templates online)
What to Do: Tara Trudo, a K–6 math specialist from Addison, Vermont, finds that her second graders struggle with accurately drawing clock hands on a blank clock for a given time. Rather than begin with written practice, she prefers to “give kids more practice with placing hands on a manipulative-based clock before drawing hands on paper.”
Explain that players will take turns rolling the dice to come up with a time to mark on their clocks, but that you’ll begin the game as a class before transitioning into pairs. For example, if your hour dice roll is an 8 and the minute roll is 40, you should work with students to arrange the clock hands to show the time as 8:40. Trudo, who blogs at The Elementary Math Maniac, emphasizes the importance of arranging the hour hand correctly—in this example, it should be between the 8 and the 9 on the clock, rather than directly on the 8.
Students can then work in pairs to play the game, writing the times rolled on their whiteboards. In this way, they practice using both analog and digital times. The player who shows the correct time first wins the round. Once students feel comfortable with manipulative clocks, you may have them put those clocks aside and play the game by drawing in hands on blank clockfaces.
Note: If you do not have clock dice, multiple dice can work in the following way: Use two six-sided dice to define the hour and two 12-sided dice to define the minutes. For example, if the first two dice show a 3 and 4, respectively, and the next two dice show 2 and 5, the time would be 7:25. You may increase the complexity by adding in more dice.
When Am I?
Standards Met: CCSS.Math.Content.2.MD.C.7; 3.MD.A.1
What You Need: Sticky notes, mini-whiteboards, dry-erase markers
What to Do: This lesson is a twist on the popular game Who Am I? But rather than having students guess a historical or famous figure by asking and answering questions, When Am I? helps to reinforce concepts of telling time and calculating elapsed time.
Prepare the game by writing different times on sticky notes. For beginners, you may write times to the hour or half hour; for advanced learners, you may choose times to the minute.
Then, start off by playing it as a class. Ask for a volunteer to place a sticky note on her forehead without looking at it. She will then ask the class questions to help determine what time she is displaying. Students should offer comments that relate to elapsed time. For example, if the sticky note says 2:42 p.m., students may say, “Your time is 18 minutes before dismissal.” Or, if the student asks what she would be doing at her time, the class might say, “We would just be finishing math.”
You may want to record the process students use to calculate the elapsed time on chart paper to track their strategies. For example, you may show a time line that breaks up the elapsed time into easier chunks (2:42 + 8 minutes = 2:50; 2:50 + 10 minutes = 3:00; 3:00 + 10 minutes = 3:10). This can provide students with reminders of how to calculate elapsed time as they continue the game in small groups.
After modeling, break students into pairs or groups of three and have them play together. They can keep track of their answers to elapsed time questions on a whiteboard. Close the lesson by discussing the best strategies for solving elapsed time problems.
Photo: Courtesy of Tammy DeShaw