Teachers who give struggling pupils "lavish praise" could make them even less likely to succeed, according to a new UK study.
The Sutton Trust education charity in UK has warned that many strategies used by teachers have no evidence to show that they really work.
Lavish praise for students is among seven popular teaching practices not supported by evidence, according to a Sutton Trust and Durham University report which reviewed over 200 pieces of research on how to develop great teachers.
Professor Rob Coe and colleagues at Durham's School of Education, warn that many common practices can be harmful to learning and have no grounding in research.
Examples include using praise lavishly, allowing learners to discover key ideas by themselves, grouping students by ability and presenting information to students based on their "preferred learning style".
On the other hand, some other teaching approaches are supported by good evidence of their effectiveness. Many of these are obvious and widely practised, but others are at odds with common assumptions.
Examples include: challenging students to identify the reason why an activity is taking place in the lesson; asking a large number of questions and checking the responses of all students; spacing-out study or practice on a given topic, with gaps in between for forgetting; and making students take tests or generate answers, even before they have been taught the material, researchers said.
Previous research shows that the quality of teaching is by far the biggest factor within schools that impacts the achievement of children from poorer backgrounds.
The report offers a "starter kit" for thinking about what constitutes effective teaching. This is based on behaviours, approaches and classroom practices that are well-defined, easy to implement and show good evidence of improvements in student outcomes.
According to the report, teachers with strong knowledge and understanding of their subject make a greater impact on students' learning.
It is also important for teachers to understand how students think about content and be able to identify common misconceptions on a topic.
Specific practices, like reviewing previous learning, providing model responses for students, giving adequate time for practice to embed skills securely and progressively introducing new learning (scaffolding) are also found to improve attainment, the report said.
