Much of the fruit we eat contains pips or stones that are the seeds of potential pot plants. Tropical fruit is your best bet and an exciting prospect for children. Temperate fruits, such as apples and pears tend to produce slow-growing plants that are less interesting. Instead, think tropical - lychee groves and date palms, flowering kumquats and passion fruit. Children may never get to pick mangoes from their mango tree, but they can learn a lot about how things grow. Other activities follow: your pupils can take measurements, plot growth curves, measure water needs and the effects of light. They can find out where the fruit comes from and how it got here. Older students may learn about genetics, grafting, natural variation and adaptation to habitats. It's the nearest most of us will get to a tropical forest outside the Eden Project.
How to do it * Choose tropical fruit that is very ripe. Remove pips, rinse in warm water and dry on a paper towel.
* Sow in a pot of moist multipurpose compost, small pips just below the surface, large ones a little deeper.
* Seal the pot in a clear plastic bag and put it in a warm, light spot.
* Check regularly, keep moist but not soaking. Seeds should start to grow in three to four weeks depending on the plant.
* Once shoots are visible, remove the bag and grow the plant on a sunny windowsill.
* After a month, start to liquid feed weekly all the time the plant is growing, but just water in late autumn, winter and early spring.
* Repot once roots start to grow out of the bottom of the pot.
Avocado Soak the stone for two days, then plant with the tip just showing. Makes a tall handsome plant with large, dark green leaves. Nip out the top at 30cm or more to encourage branches and control height.
Citrus * Sow seeds in a mix of three parts compost to one part sharp sand for extra drainage. Citrus are easy to grow and produce bushy plants with scented, glossy leaves. Lemons and kumquats are the most likely to produce flowers and fruit after a few years.
Mango Clean the stone, then rub with sandpaper to help water penetrate. Soak in water in a warm place, changing the water every day. Pot up when it sprouts, or after two weeks. Germination time is about five weeks more. Mangoes grow quickly. Nip out the tips to make the plant smaller and bushier. The leaves are long and shiny.
Peanut Buy nuts in shells - others will be too dry to grow. Crack the shell, but leave the nuts in place and plant the lot. Do not feed the plants or they will not flower, and stand them outside in summer, so bees can pollinate them. Yellow flowers are followed by little pods that grow down into the compost. The plants die in autumn and you can dig up the peanuts.
Lychee Needs a warm spot to germinate. Once germinated, keep in the shade for a few weeks, then in indirect sunlight. Keep moist at all times and spray with water. Has lovely glossy, pointed foliage that turns orangey-red in spring.
Passion fruit Use black or orange passion fruit. The plants can go outside once all risk of frost has passed, and will make vigorous climbers. In mild areas they can overwinter outdoors, otherwise bring indoors in autumn. On a warm, sunny spot they should flower and maybe fruit in their second year - this is less likely if they are kept indoors.
Others to try Cape gooseberries will produce pretty cream flowers in summer and tangy, sticky fruit in autumn. Dates can be slow to germinate but make easy-to-care-for miniature palm trees. Ginger root produces grassy leaves and scented greeny-purple flowers. Pineapple tops, if cut when fresh, can be coaxed into leafy life.