Introduce a scenario. For example, you could show students a recipe that yields six dozen cookies. Explain that you only want to make three dozen cookies. Ask for ideas on how you can still use the recipe but make fewer cookies.
Illustrate the concept by drawing a picture or using tactile examples. For the problem above, you could draw six cookies on the board and circle three of them. This visual will help students to recognize that if the yield is cut in half, the recipe must be cut in half.
Discuss possible ways of finding the solution. Many students will automatically think of dividing the ingredients by two, but some students may think to divide the ingredients by six to determine how much is in each dozen and then multiply that times three to get the amount needed to yield three dozen cookies. Listen to the students' ideas with an open mind.
Write the problem out on the board. If multiple ideas are given, write the problem out according to each suggestion. This allows students to see multiple ways of arriving at the same answer.
Allow the students to teach. Once the students are getting a grasp on the concept, allow them to demonstrate a problem to you or the class. As they solve the problems, encourage them to explain what they are doing and why.
Place students in groups of two or three, and allow them to work on different scenarios together. The purpose of this exercise is not necessarily to arrive at an answer, but rather to come up with different ways to solve the problem.
Be flexible. Conceptual math can only be taught if you get outside the box of "This is the way I've always done it." Give your students the knowledge to understand mathematical concepts and the freedom to solve problems using their own methods.