Sensim Math · Depth 한국어

2-2 · Time

Read the hour when the hand is between

2.MD.C.7 · take · grade 2

Archetype: Elapsed Time and Base-Sixty Regrouping · step in a 10-type progression

▶ Practice — 10 problems

On a clock, the minute hand points 3 small tick marks past the number 9, and the hour hand is between the numbers 8 and 9. What time does the clock show, in hours and minutes?

12 1 2 3 4 5 6 7 8 9 10 11
Show solution

Understand

An analog clock has its long (minute) hand 3 small ticks past the 9, and its short (hour) hand sitting between the 8 and the 9. I need to read off the time in hours and minutes.

Givens
  • The minute hand points 3 small tick marks past the number 9.
  • The hour hand is between the 8 and the 9 (closer to the 8).
Unknowns
  • The time the clock shows, written as hours:minutes.
Constraints
  • Each number on the clock is 5 minutes apart for the minute hand.
  • Each small tick is 1 minute.
  • When the hour hand is between two numbers, the hour is the smaller of the two.

Plan

#1 Draw a Diagram · also uses: #5 Look for a Pattern

Reading a clock is a picture-reading task: I locate each hand on the dial. The minute marks follow the steady pattern of 5 minutes per big number, so I count from 12 to the 9 and add the extra ticks. The hour hand position tells me which completed hour we are in.

Execute

#1 Draw a Diagram 2.MD.C.7
The hour hand sits between the 8 and the 9. The clock has not yet reached 9 o'clock, so we are still in the 8 o'clock hour. The hour is 8.
A Grade 2 reader knows that until the hour hand reaches the next number, the hour stays at the smaller number.
#5 Look for a Pattern 2.MD.C.7
Each big number is 5 minutes apart. Counting by 5s from the 12 to the 9 gives 5, 10, 15, 20, 25, 30, 35, 40, 45 — so the 9 is the 45-minute mark. Then add the 3 small ticks (3 more minutes): 45 + 3 = 48 minutes.
9×5=45,45+3=489 \times 5 = 45,\quad 45 + 3 = 48
Skip-counting by 5 to each number, then counting single ticks, is exactly how Grade 2 students read minutes.
#1 Draw a Diagram 2.MD.C.7
The hour is 8 and the minutes are 48, so the clock shows 8:48.
Putting the two hand readings together gives the full time.
Answer: 8:48

Review

48 minutes is less than 60, and at 48 minutes the hour hand should be almost all the way from 8 toward 9 — but still before 9 — which matches 'between 8 and 9, closer to the 8 side of the gap.' The reading is consistent.

Instead of counting up from 12, notice the 9 is the 45-minute mark and the long hand is 3 ticks beyond it; 45 + 3 = 48. Same answer, using the known landmark of the 9.

Standards · min grade 2

  • 2.MD.C.7 Tell and write time from analog and digital clocks to nearest five minutes — Reading the hour from the short hand and the minutes from the long hand, then writing the time.
💡 This only needs the Grade 2 clock skill of counting by 5s to a number and adding the extra ticks!