Nine elapsed-time problems for 3rd grade built around the open number line strategy. Maya reads for 45 minutes from 3:15 p.m., Caleb's violin practice runs 4:20 to 5:05, and a planetarium show must be worked backwards from its 11:35 a.m. finish. The final section is a Saturday schedule table with four activities and four gaps to fill, mixing missing end times, start times, and durations. The answer key writes out the jump strategy for every single answer.
3.MD.1
“Tell and write time to the nearest minute and measure time intervals in minutes. Solve word problems involving addition and subtraction of time intervals in minutes, e.g., by representing the problem on a number line diagram.”
All nine problems add or subtract time intervals in minutes, with the number-line jump strategy named in the Part 1 instructions and modeled in every key answer.
Two illustrated problems ask students to show their jumps (+10 min, +5 min, +1 hour): Maya finishing her book at 4:00 p.m. and Caleb's 45-minute violin session.
Three problems force a choice between adding and subtracting: the 50-minute planetarium show ending at 11:35, muffins in the oven from 9:48 for 24 minutes, and Sofia's soccer practice from 5:15 to 6:30.
A four-row table (bike ride, art workshop, park picnic, board game) hides one value per row. Students compute a missing elapsed time, end time, start time, and elapsed time in turn.
Strategy lesson
Draw the open number line for problem 1 on the board: 3:15, a +45 jump, land on 4:00. Then let Part 1's second problem test whether students can chunk 4:20 to 5:05 themselves.
Backwards thinking
Problem 3 is the pivot: the show ends at 11:35, so students must run the line in reverse. Set it as partner work before anyone tries the schedule table.
Real-schedule extension
After Part 3, have students build one row of their own Saturday schedule with a hidden value and swap with a neighbor to solve.
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