Math · Unit 5 · Weeks 25–30
Time, Measurement, Area & Perimeter
The big idea
Your child tells time to the minute and solves elapsed-time problems on a number line, then measures mass in grams and kilograms and liquid volume in milliliters and liters. After the Quarter 3 review, the unit turns to area, first by covering shapes with unit squares and then by multiplying side lengths, and ends with perimeter, the distance around a shape.
Standards in plain words
- 3.MD.A.1 Tells and writes time to the nearest minute and solves word problems about time intervals in minutes, for example on a number line.
- 3.MD.A.2 Measures and estimates mass in grams and kilograms and liquid volume in liters, and solves one-step word problems that use the same unit.
- 3.MD.C.5 Understands area as the amount of flat space a shape covers, measured with unit squares that leave no gaps or overlaps.
- 3.MD.C.6 Measures area by counting unit squares (square centimeters, square meters, square inches, square feet and made-up units).
- 3.MD.C.7.a Finds the area of a rectangle by tiling it and sees that multiplying the side lengths gives the same answer.
- 3.MD.C.7.b Multiplies side lengths to find the areas of rectangles in real-world and math problems.
- 3.MD.C.7.c Uses tiles and area models to show that splitting one side of a rectangle splits its area into two parts that add up, which is the distributive property.
- 3.MD.C.7.d Finds the area of a shape made of rectangles by splitting it into rectangles that do not overlap and adding their areas.
- 3.MD.D.8 Solves perimeter problems: finds the perimeter from the side lengths, finds a missing side, and shows rectangles with the same perimeter but different areas, or the same area but different perimeters.
What mastery looks like
- Reads an analog clock to the minute and finds start times, end times and elapsed times within an hour, jumping to the hour on a number line.
- Estimates and measures mass and liquid volume, chooses grams or kilograms, and answers with the right unit.
- Finds area by counting unit squares and by multiplying side lengths, and labels it in square units.
- Finds the area of an L-shape by splitting it into two rectangles and adding the areas.
- Finds the perimeter of a polygon and a missing side when the perimeter is known.
Materials
- Analog clock with movable hands (or a paper plate clock)
- Paper for open number lines
- Kitchen scale that shows grams
- Measuring cup marked in milliliters and a 1-liter bottle
- Square tiles or paper squares
- Centimeter and inch grid paper
- Ruler and yarn or string
- Two colors of crayon
Watch across the unit
Watch for: Treating an hour as 100 minutes, or subtracting minutes straight across the hour (20 minus 45).
Try: Mark the hour on an open number line, jump to it first, then add the minutes that are left.
Watch for: Adding side lengths for area (5 + 8) instead of multiplying, or leaving off 'square' in the unit.
Try: Build the rectangle with tiles and count; ask 'Did you measure a line or cover a space?' A covered space needs square units.
Watch for: Mixing up area and perimeter in word problems.
Try: Ask 'Am I covering the inside or going around the edge?' and have your child tap the inside or trace the outside with a finger.
Pacing
Short week: Keep Monday's lesson with the clock, scale or tiles and the Friday check. The kitchen measuring and real-world area problems can shrink to one example each. Do not drop the Week 30 day on finding a missing side; it returns in Unit 6.
Flex week: This unit has no flex week. Week 27, the Quarter 3 review, does the same job for fractions, time, measuring and mass: use the Week 27 practice set to find skills to revisit, and give extra time to whichever area or perimeter day was hardest.
Week by week
| Week | Topic | Check |
|---|---|---|
| Week 25 | Time to the minute & elapsed time | Solve time word problems |
| Week 26 | Mass (g, kg) & liquid volume (mL, L) | Measure and solve one-step problems |
| Week 27 | Quarter 3 review | Quarter 3 cumulative check |
| Week 28 | Area with square units | Find area by counting unit squares |
| Week 29 | Area with multiplication & addition | Find area of rectangles and combined shapes |
| Week 30 | Perimeter | Unit 5 test |