About this time of the year (autumn and winter), you can buy Amaryllis bulbs in the shops. All you have to do is water them each week and keep them warm (minimum 20oC). When the flower bud appears then you must water the soil about twice a week, and they will produce the most beautiful flowers.
But Amaryllis also offer a whole range of opportunities to look at numeracy, including drawing graphs, considering symmetry, and carrying out investigations. This teachers' sheet introduces you to some of these ideas.