Reading a clock

Reading an analog clock is typically hard for young learners in primary school as well as for people suffering from dementia.<ref>Sunderland, T., Hill, J. L., Mellow, A. M., Lawlor, B. A., Gundersheimer, J., Newhouse, P. A., & Grafman, J. H. (1989). Clock drawing in Alzheimer's disease: a novel measure of dementia severity. Journal of the American Geriatrics society, 37(8), 725-729.</ref> In Decoding the Disciplines clock reading often serves to exemplify the process of Decoding.<ref name=":0">Riegler, P. (2025): The Decoding Clock Reading Activity. Didaktiknachrichten, Issue July 2025</ref>

Clock from 1754 at Irsee Abbey, Germany. What time does it show?

Description of bottleneck

People find it hard to read of the information coded by the hands of a clock and translate this information into a valid description of clock time.

Description of mental tasks needed to overcome the bottleneck

• There are two scales on an analog clock. A coarse one counting the hours from 1 to 12 in steps of 30° and a finer one counting minutes and seconds from 0 to 59 in steps of 6°.
• If there is a fast moving hand, ignore this one for the time being, although it typically catches one's attention first.
• To determine the hour, locate the hour hand. This is usually the shortest hand. Read the position of this hand on the scale from 1 to 12. If the hand is between two such positions take the smaller value.
• To determine the minutes, locate the minute hand. This is usually the larger hand. Read the position of this hand on the scale from 0 to 59.
• While the lengths of the hand usually allows to locate hour and minute hand, the length of the hands is neither a necessary nor a sufficient conidition. Actually there is a necessary relation between the angle of the two hands: The fractional part by which the minute hand is located between two adjacent hour markers is determined by the position of the minute hand. For instance, at 5:00 the hour hand is exactly at 5, at 5:15 it moved a quarter of the disctance to 6, while at 5:30 it is exactly between 5 and 6.<ref name=":0" />
• If there is a fast moving hand, it indicates the seconds analogously to the minute hand.

Related scholarly work on this bottleneck

The paper The Decoding Clock Reading Activity describes the origin of the activity and provides materials.

People interested in this bottleneck

Christian Kautz, Peter Riegler

Available resources

• Photographs of unusual clock faces

References

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