Parents, first usually ask me how to take a temperature at the one or two month visit.
At that age, I usually suggest to them that they use a rectal thermometer, if they are going to take their temperature at all. I caution them that infants tend to run lightly higher temperatures than older children. Up to 100.5 rectally, is a normal temperature for an infant, in the first few months of life.
Secondly, once a child achieves the age of 6 or 7 years, they can use an oral thermometer. That's a safe thing to do, by that particular age.
There are a number of gizmos on the market, that parents use to take temperature. Fever strips are one of them, an ear thermometer is another, are some of the things that parents have bought. I am not a fan of these products, as they often lead to incorrect results, but parents tend to like them. It gives them security, so we do the best we can with the temperatures that we get from those.
At the end of the day, there isn't a big difference to your physician whether the child's temperature was 101.2 or 102.8. While it is important to take their temperature, on occasion, it is not critical that we get it right.