The cute, furry hamster in the cage in the corner may be a no-no and windows might have to be closed at the start of term when the pollen count is still high. If it's chucking down, hanging up wet clothes to dry also carries risks - but opening windows may prevent condensation.
One minute windows are open, the next shut - just some of the complexities of coping with asthmatic pupils in the classroom.
It is unlikely that probationers starting next month will have little else on their minds than coming to terms with discipline - always their number one priority - lesson plans and assimilation into school life, but they could also be faced with a range of pupil conditions and illnesses that will test their responses.
One in eight pupils has asthma and could easily suffer an attack early on. A new study guide on children's health, backed by the Scottish Executive, and aimed at new recruits to the profession, highlights some of the main challenges in the classroom or playground.
Asthmatic pupils will be the most common health concern. Anything from furry animals to particular foods, dust mites and pollen may trigger an attack, according to the Executive-promoted booklet, written by health education specialists at Strathclyde and Aberdeen universities. "Pets should be bathed weekly," they advise - if you have them in the first place if you are asthmatic.
Other triggers may be chemicals from science and art classes or strong smells and cold air. "Exercise is good for people with asthma if they have it under control: avoid exercising on cold days and warm up sufficiently before any exercise class," the experts caution.
The authors suggest teachers compile an asthma register and be aware which of their pupils carry inhalers. If an asthma incident occurs, teachers must remain calm and ensure the safety of the child. The inhalers children carry will generally open their air passages and help breathing.
"Many children are open about having asthma and it is often discussed in a normal way in class: nevertheless, having an attack in the playground can be embarrassing," they point out.
In class, asthma might be brought in as a health education topic and children may be willing to contribute their experiences.
Meanwhile, one in 700 children has diabetes, "therefore, in your teaching career it is highly probable that you will teach a child with this condition", the advisers continue. Most children diagnosed with diabetes will have two injections of insulin a day and must have a balanced diet to maintain blood glucose levels. A "hypo" occurs when blood sugar is low. Symptoms include hunger, glazed eyes, lack of concentration and sweating.
"Ideally, a fast-acting sugary food should be kept in a desk drawer or filing cabinet and be accessible at all times," the team recommends.
Similarly, around one in 100 children will have epilepsy at some time in their young lives. Seven out of ten of them are likely to have it controlled by medication within two years of diagnosis. Teachers need to be aware which children have the condition and know their first aid procedures.
The advisers emphasise: "When a seizure takes place in a classroom or at an assembly, all children are affected. They may be genuinely afraid for the well-being of the child. They will be upset at seeing a classmate who appeared to be fit and healthy ten minutes ago, but is now looking unwell or strange in behaviour and speech. When this occurs, children need to be given factual information appropriate to their age."
Teachers need to be wary of possible incidents of name-calling or other forms of bullying and observe changes in a child's behaviour, ability or attainment. "A wide range of factors may affect how well a child with epilepsy performs at school," the team points out.
'A Study Guide on Children's Health' is on the Scottish Executive website. Its authors are Joan Forrest and Lesley Beaton, of Strathclyde University, and Yvonne Dewhurst and Jackie Stewart, of Aberdeen University.