The summer term is traditionally seen as the dog end of the school year for many pupils - when hot classrooms, a desire to play in the sunshine and inevitable post-Sats relaxation might be expected to slow academic progress.
But new Government research has found the opposite is true. Key stage 2 and 3 pupils make most progress during the summer term and least during the longer autumn term.
The Department for Education study analysed teacher assessments made at the end of each term for 37,000 pupils in more than 340 schools. The records, for five different cohorts of pupils over three years, showed the same pattern of progress - in national curriculum levels of achievement - between autumn, spring and summer terms in reading, writing and maths.
The researchers linked the smaller increase in the autumn term to the long summer break "requiring pupils to retain their learning from the previous academic year over several weeks away from school".
They also noted that most primary pupils would be getting used to a new teacher during the autumn term.
"A teacher who is just getting to know their class may have less information about what each pupil can achieve on which to base their assessment," the report says.
It notes that: "The spring term is typically a few days shorter than the autumn or summer terms, giving a little less time for teaching and learning to take place."
The study also found that pupils were more likely to regress during the autumn term.
Professor Alan Smithers, from Buckingham University, said: "This is very interesting research that raises more questions than it answers.
"It points to the effect of the long summer holiday, which can break the momentum of learning. But it would be interesting to see whether that affects some students more than others because of their home backgrounds.
"It could just be that if it is wet and miserable in the autumn and early spring that people are less enthusiastic and that teachers and pupils are more cheerful and dynamic in the summer."
The research - based on data collected during the Government's aborted pilot of single level tests - also found that many pupils did not achieve steady, continuous progress.
Their patterns of progress were "highly individual", particularly in reading and writing.
TAKING A DIP
The research also revealed that the more progress a pupil made in one term, the less likely they were to make progress the following term - and vice versa.
The study provided further evidence of a key stage 3 dip, with more progress made every year in KS2 across all three subjects, but particularly in reading and writing.
Boys were less likely to progress than girls in all three subjects.
The gender gap in progress widened every year in KS3 and was biggest in reading, smallest in maths.
Chinese pupils progress the most, especially in maths. Unlike other ethnic groups, who may be "catching up" during KS2 and 3, Chinese pupils are already ahead of white pupils in attainment of the expected levels at KS1.