Draw a basic flower with a pencil on a piece of paper. You can get a picture of a sample flower from a encyclopedia, magazine, or online. Children tend to understand drawings best when being taught new things, and drawings are an ideal medium for third-grade children to learn from. It does not matter what type of flower you draw -- a rose, tulip, or lily, for example -- as long as you include the full image of a flower.
Draw a line from the petals of the flower out towards the blank area on the page. Label this as the petals. The petals are the soft, colored pieces that extend around the perimeter of the flower.
Draw a line from the small, outer stems on the inside of the flower out towards the blank area on the page. Label this area as the stamen. The stamen, made up of the anther and the filament, is the male part of a flower, the pollen producing part of the plant. Stamen can come in varying numbers, depending on the particular genus of flower.
Draw a line from the inner stem from the inside of the flower out towards the blank area on the page. Label this area as the pistil. The pistil, made up of the stigma, style, ovary and ovule, is the female part of a flower, which is constructed of leaf-like structures.
Draw a line from the supporting stem on the underside of the flower out towards the blank area on the page. Label this area as the stem. The stem of a flower, typically divided into nodes and internodes, is the part which holds the flower up to allow it to be seen by insects and pollinated. Some stems, such as rose stems, have prickly thorns along the length, while others, such as tulip and lily stems, are smooth and soft.