See this on the BBC Four Botany: A Blooming History for a clearer picture when using with students.

This video clip from the BBC (from the TV series Botany: A Blooming History) introduces the ideas of inheritance of characteristics, with a discussion of Mendel's research into patterns of inheritance in pea plants.

The vast range of diversity of form and function in the plant kingdom was a major puzzle for 19th century botanists and continues to be important for modern day geneticists. Variation is observed in all species and offspring have a unique combination of the characteristics inherited from their parents. Since Darwin, biologists have studied the way that the characteristics are passed on. In 1866, Gregor Mendel published work on patterns of inheritance in pea plants. He bred many generations of plants and noted the ratios of inherited characteristics. This new and very scientific approach generated patterns in the ratios which no-one had seen before. Unfortunately, at the time his work was not understood and its importance was not appreciated.

Use to introduce a lesson on the history of science and ideas. Introduce the ideas of inheritance of characteristics and lead into a discussion of the characteristics which Mendel studied and the ratios he established. Students could do similar breeding experiments with tomatoes or rapid cycling brassicas. Other interesting activities include observation of variety in humans, apples, roses, fish etc. From this point, it is also possible to look at the mendelian ratios and the mechanisms of inheritance which he proposed.