Easy poster that helps students remember the steps to prime and composite numbers. If the student memorize the questions, prime and composite number become second nature.
I usually show a number strip with 4 double-digit numbers on it with only one being prime. I have the student go through the questions. As the student asks the first question (Is the number even?) I cover up any even numbers up with my hands/fingers. And continue through the questions until there is only one remaining number (which MUST be prime). This helps them memorize the questions to ask and soon they memorize the two digit prime numbers.
My students learn prime and composite numbers within 3 days using this strategy.