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Ratios and Data 6-8 / Week 05 / Data Day
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Week 05 · Decimals, Factors and Multiples

Data Day

Data Day: Measure a room
// Long division, decimal points, and what two numbers share
⏱ about 20 min

Data Day: Measure a Room

Saturday morning the crew carries the tape measure into the living room. "Data Day," Rocket announces. "Every wall gets measured."

"To the hundredth of a meter," says Raven. "What do you notice about the two long walls?"

Rocket reads the tape. "4.25 meters. And the other one, 4.25. They match."

Nova hovers near the corner, holding the tape end steady. "Add all four," she says. "That is one lap around the room."

"Then we pack the kits one more time," Raven says, "and count the badges by twelves."

Rocket grins. "And next week the thermometer goes below zero." Nova hums. "Bring a warm jacket."

  1. Long division: divide, multiply, subtract, bring down. 1,500 ÷ 12 = 125, and 12 × 125 = 1,500 checks it.
  2. Add and subtract decimals with the points lined up: 12.75 + 8.4 = 21.15.
  3. Multiply decimals by counting the places: 2.5 × 1.2 = 3. Divide by moving both points: 4.5 ÷ 0.5 = 9.
  4. The GCF of 36 and 48 is 12: twelve equal kits. The LCM of 6 and 8 is 24: the timers beep together at 24 seconds.
  5. The distributive property writes a sum as a multiple: 36 + 48 = 12 × (3 + 4).
◇ MEASURE A ROOM WITH A GROWN-UP
Pick a room. One person holds the tape end at a corner, the other reads the length of each wall.
Write each wall in meters with two decimal places. Measure each wall twice.
Add the four walls with the decimal points lined up. That is the distance once around the room.
Multiply by 3 for three laps. Then divide one lap by 4 to find four equal rest stops.
Count two kinds of objects in the room, like chairs and cushions. Find the GCF of the two counts.
For a grown-up
This week your student divided multi-digit numbers, worked with decimals and found the GCF and LCM.
Ask them to show you 12.75 + 8.4 in a column with the points lined up, and why 13.59 cannot be right.
A metal tape measure snaps back quickly. Please rewind it yourself, slowly.
Safety first
Let a grown-up rewind a metal tape measure. Keep fingers clear of its edge.
Move slowly around furniture, and keep the tape off the floor where someone could trip.
DATA DAY CHECK
  • Read the question.
  • Tap your answer.
A room has walls of 4.25, 4.25, 3.5 and 3.5 meters. How many meters once around?
Once around the room is 15.5 meters. How many meters is three laps?
Four rest stops are spaced equally around 15.5 meters. How many meters apart?
8 chairs and 12 cushions go into equal groups with nothing left. How many groups at most?
Draw your room from above with each wall labeled in meters to the hundredth.

Great measuring, crew. Next week: numbers below zero, opposites, and the four-quadrant map.

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