Try to pair up each fresh with dried herb, or dried herb with herb essence, or fresh herb with herb essence.
Herbs may smell strong to discourage animals from eating them.
You can smell the herbs and spices because some of the molecules leaving the herb or spice go up your nose and interact with molecules in your nose. We smell them when their unique shapes fit like jigsaw pieces into the inside of our nose, and stimulate a nerve signal to our brain, which we perceive as smell.
Pair up fresh herb with smell of dried
Students smell the real herbs, by brushing their hands against them then smelling their hands.
Match with bags of dried herbs, whose identity is hidden (see photos).
The pairs of fresh herbs/dried herbs/essences probably didn't have exactly the same smells as they all release slightly different mixtures of smell molecules.
However there is often a main molecule responsible for each distinctive herb smell, so we cue into this odour molecule to match the smells.
Each of the smells has many molecules making it up, but sometimes a predominant molecule that is responsible for the smell:
Oregano has the molecule carvacrol in its smell. Anise seeds have the molecule anethole in their smell. Cloves have eugenol in their smell. Mint has L-carvone in its smell. Garlic has allyl- disulphide in its smell. Rosemary has eucalyptol in its smell.
Optional: show molecule models of the predominant smell molecules in mint and marjoram smells (see photo):
See if students can spot the difference between the molecules responsible for mint and marjoram smells.
Although the chemical shapes are similar, they smell very different.
Most smells are complex mixtures of many molecules so smells often mean something quite different to each of us.
Pair up plant part with smell of essence
Squeeze and sniff the smelly bottles (containing essences). Look at the plant pieces inside the glass jars. Match them up.
Students can also try and match each smelly bottle and jar of plant pieces with a picture of the plants they come from.
For younger students, duplicate the smelly bottles, and ask them to match up the ones that smell the same - use fruity smells too.
For very young students make into a game, where each table is a team. All tables are given the same-smelling tube at one time. The students at a table work together to try and guess what the smell is, and write it down. When the time is up, they hold up their written answer.
Optional for older students: which part of the plant dos each plant piece come from? (Leaves, flowers, seeds, bark or trunk?)
Coffee beans are seeds.
Cedar wood is the trunk.
Lemons are the fruit.
Lavender is the flower.
Oregano is the leaves.
Cinammon is the bark.
Garlic is the bulb (underground leaves).
