Reasoning · Grade 2-2 Exploring Clocks
Problem
The mirror flips the dial sideways, so real + mirror = 12.
Drawing the flipped clock makes the 12 - h rule visible; reading an analog hour is a Grade 2 skill.
2.MD.C.7Draw A DiagramHolding the clock to a mirror sends the hour h to 12 minus h, because the mirror line runs through 12 and 6.
The mirror sends each hour mark straight across the 12-to-6 line to the mark the same distance away on the other side.
Reflecting does not stretch the dial, so the hand keeps its length and the spacing of the hour marks stays even.
For each hour, measure how far apart it and its mirror sit.
Subtracting from 12 and finding the gap are simple Grade 2 add/subtract steps done case by case.
2.OA.A.1Make A Systematic ListA gap of 2 gives 1, 5, 7, 11.
The matching hours are spaced evenly around the dial - a tidy pattern that confirms the group is complete.
3.OA.D.9Look For A PatternA gap of 4 gives 2, 4, 8, 10.
Same even spacing pattern, shifted - four real times share this difference.
3.OA.D.9Look For A PatternA gap of 6 leaves only 3 and 9; 6 and 12 drop out.
A 6-hour gap means the hands are straight across from each other, which only 3 and 9 satisfy here.
3.OA.D.9Look For A PatternIn a mirror the clock's hours always add up to 12, so once you know that, sorting the times by their gap is a pattern you can see right on the dial!