But the problems can often be solved with quite simple teaching methods, according to the latest findings of the Primary Review.
A report by academics from the Institute of Education's Teaching and Learning Research Project (TLRP) outlines the conclusions of 19 primary research projects. These focused on the most effective ways to ensure pupils learn.
Researchers found primary pupils of all ages struggle with irregular spellings, such as "rough" or "station". But these problems can be reduced by teaching pupils to recognise morphemes, or sections of words, such as "-tion" or "-ence".
Most pupils in Years 4 and 5 also struggle with the concept of fractions. But this can be avoided by appealing to pupils' understanding of division or sharing. "Two or three hours of teaching can boost children's understanding and their use of fractions," the researchers said.
The researchers also found that using ICT helps pupils to move smoothly between individual learning and broader, teacher-supported learning, and that pupils benefit from being consulted about their education. So teachers should question ingrained habits of relating to pupils, and encourage classroom-based enquiry.
The researchers said: "Many barriers to pupils' participation and learning stem from teachers' misplaced assumptions about what pupils can do, and how best to teach them."
As The TES reported last year, the TLRP has produced a series of 10 principles, designed to distil their findings for teachers.
These include the recommendations that pupils should be encouraged to address "big ideas" and "key processes", that teachers recognise the value of out-of-school informal learning, and that staff be given regular access to professional development.