Draw two equal sized circles on the chalkboard. Tell students the circles represent pizzas or pies to capture their interest.
Divide both circles into thirds and count the thirds of both circles with the students.
Shade two thirds of each circle. Label the thirds on one circle and write "2/3" beneath both circles to represent the shaded fraction of the circles. Remind students that the denominator represents the total parts and the numerator represents the shaded parts.
Divide the other circle into sixths by dividing each third in half. Label the sixths on this circle.
Show students that circle 1 contains thirds and circle 2 contains sixths. Explain that both circles make up a whole, with the parts being fractions. Show students that the 2/3 fractional part on circle 1 and the 4/6 fractional part on circle 2 are equal or equivalent.
Draw two circles. Divide both circles into halves and shade one-half of both circles. Show the equivalent fractions by dividing each half of the second circle in half (dividing the fractions by two). Write 1/2 = 2/4 on the chalkboard and show students that because you divided the halves in circle 2 by two, you must multiply both the numerator and denominator of the first fraction by two 1/2 * 2/2 = 2/4 -- the equivalent fraction.
Illustrate the concept with another example. Draw two more circles. Divide both circles into thirds and shade one-third of both circles. Divide the thirds of the second circle into thirds to make nine parts. Write 1/3 = 3/9 and remind students that because you divided the thirds in the second circle into three parts, you multiply the numerator and denominator of the first fraction by 3. Write 1/3 * 3/3 = 3/9 -- the equivalent fraction.