Tell students that a fraction is a number that represents part of a whole. Tell them that when things are divided into fractions, they're often divided into equal parts.
Draw a picture of a circle on the board and then draw a line down the middle of the circle from top to bottom. Shade in one side of the circle. Ask students to tell you how many parts the circle is divided into. When they say two, write a horizontal line and write 2 under it. Next ask them how many parts are shaded in? When they say one, write 1 above the line. Tell students that when things are divided into two equal parts it's called half, this picture is half and this is how 1/2 is written.
Draw a picture of a circle on the board except divide the circle into three equal parts by drawing a peace sign in the middle of it. Shade in one part of the circle. Ask students how many parts does the circle have? When they say three, write a horizontal line and write 3 under it. Next ask them how many parts are shaded in? When they say one, write 1 above the line. Tell students that when things are divided into three equal parts it is called thirds, one third of the circle is shaded in and this is how 1/3 is written.
Repeat the process to teach ¼ except divide the circle into four equal parts so that it looks like a window. If students are more advanced, also introduce 1/6, 1/8 and 1/10 using a rectangle.
Check student understanding. Give six students pictures of the fractions introduced in the lesson and give six students the numerical representation of the pictures of fractions. Pass the pictures and fractions out mixed up and tell students to find their partners. For example, a student with the picture of one out of four parts of a rectangle shaded in should know their partner is the person that has 1/4 written on their card. If there are any students left over, create more challenging pictures and fractions for higher performing students so they can find each other. There are Internet games that can be played as a whole class to check understanding.