ingridscience

Bees collect pollen, to feed growing bees in the hive.
Pollen can be different colours, to attract bees.
Once students know that the pollen is on the anthers of a flower, give them magnifiers to find it, look at it closely, and find out what colour it is.
(Tulips have black pollen. Orange lilies purchased in florists have red-brown pollen. Fireweed has green pollen.)
Give them pipe cleaners to gently touch the anthers to pick up pollen.

Crush the plants on the worksheet, to show what colour dyes they contain. The colour may change depending on the chemistry of the paper, and some colours will fade with time as light changes their chemistry.

Crushing to extract the juice from a plant is one of the methods used in plant preparation. Other Indigenous methods for preparing medicinal plants (from J Ethnobiol Ethnomed. 2012; 8:7):

Optional art project to make a card:
Lay pieces of fern on a piece of the cloth in a design you like.
Tape the ferns to the cloth. Make sure they are completely covered with tape.
Use the hammer, or a rock, to pound the ferns onto the cloth. Smash the ferns completely, so their colour transfers to the cloth.
Peel the tape and ferns off the cloth.
Open the card and put a few drops of glue around the edge of the window.
Lay your cloth fern design over the window, so that it is held in place by the glue.
A beautiful card made form a natural dye!

Green leaf chemistry:
The green colour in the fern leaves is called chlorophyll. In living plants, chlorophyll traps the sun's energy for plants to grow.
Indigenous groups have been making dyes from plants for thousands of years. The leaves, petals, bark and seeds of plants have all been used to make different dye colours.

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).

Two tubes contain tomato, two tubes contain banana and two tubes contain strawberry.
Smell the tubes and find the pairs.

For each pair, one tube contains ripe fruit and one contains unripe fruit.
Can you smell which is ripe and which is unripe?

Check your smells by pulling the sleeve down off the tube.

What's going on?
As a fruit ripens it makes new chemicals that change its smell.
Ripe smells attract animals, which eat the fruit and spread the seeds.
Fruits also change colour as they ripen, also to attract animals.
What colour is your favourite fruit before and after it ripens?

Each player picks up a bingo board (see attachment).
Each player chooses 4 of the bingo picture cards (see attachment), making sure that different players choose a different set of picture cards.
Glue each of the bingo picture cards to its own square of the bingo board.
Take your bingo boards into the garden/park. Find the things on your bingo card. First to find them all calls BINGO!

Smell and look at the cut flowers. Use the clues below to find out which insects would be attracted to each flower.

Bee: I like yellow, white, blue and purple flowers. I like flowers that smell sweet.
Butterfly: I like all coloured flowers - and unlike most other insects, I can see red. I like flowers that smell sweet.
Fly: I usually pollinate white, green, yellow or brown flowers. I like flowers that might smell funky to you - they have a strong smell that is not all sweet.

Or go outside on a sunny day when flowers are out and observe what insects land on them. Record what you find: what insect lands on what flower, the colour and smell of the flower.

What’s going on?
Each flower is adapted to attract one or more kinds of insects to it. When the insects collect nectar to eat, they move pollen from one flower to another. The pollen fertilizes the fowers.

Smell the fragrant leaves, flower petals and fruit peels. Choose two or three that you like best. Pick out one leaf, petal or piece of peel from each of your chosen plants. Tear the leaves/petals/peel into small pieces and put them in the mortar.
Add one spoonful of water. Grind with the pestle - push down while you grind in a circle. Grind until the plants are completely mashed up.
Suck up the perfume with a dropper. Put the perfume in a small tube to take home. Think up a fancy name for your perfume. (Your perfume will smell nice for just a day or two, so use it soon!)

What’s going on?
You used water to extract the fragrant chemicals from the plants. Professional perfume makers also extract fragrant chemicals from plants using water, or other solvents. Then they mix different fragrances to design new perfumes.

Please note that in a class of students it is likely that one of them is at least partially colourblind (1 in 12 males are colourblind). As this is an activity distinguishing colours, these students will not be able to tell some colours apart and perceive some colours differently, although the activity will be no less interesting for them. The common red/green colour blindness means reds and greens (or colours containing reds and greens such as browns) look similar. More information at colourblindawareness.org and colorblindguide.com/post/the-advantage-of-being-colorblind.

Pick a petal from the flower (use one rose petal, one camellia petal, 4 bluebell flowers, or equivalent).
Tear the petal into small pieces and put them in the mortar.
Add one teaspoon of water. Grind the petal and water together with the pestle: push down while grinding in a circle. Keep grinding until the water is as dark as the petal. It’s important that you get the water really dark.
(If you are not using a mortar and petal, tear the petal into pieces and put in a baggie with the water, then smash and squish the petal in the baggie until the petal juice is dark.)
Suck up the petal juice with a dropper. Put a few drops of petal juice in each well of the tray. Add a drop or two of acid (vinegar) to one well of the petal juice in the tray. Add a drop or two of base (baking soda solution) to another well. What new colours do you see? Are any of them familiar flower colours?
(acid makes the petal juice pink/orange; base makes it purple/blue (and green with some flowers).
Experiment with adding various amounts of acid and base to the petal juice.
Can you reverse the colour changes?

Ask students to record the changes they find, or visit the groups and record their results on one board (organizing the colours as they are reported). In class discussion, distill out the most frequent colour results in acid (oranges and pinks) and in base (blues and purples). White flowers can stay white in acid and turn yellow in base. Some colours will not change (generally yellows, oranges).

Just like you can make different colours by adding acid or base, some flowers are red, purple or blue depending on the levels of acid or base in their petals. They contain colour molecules (pigments) called anthocyanins that change structure slightly depending on the amount of acid or base they are in - one structure is red and the other is blue. Depending on the mix of red and blue anthocyanin molecules, the colour can vary between pink/red/purple/blue (all the colours you saw in the activity), giving rise to a great variety of flower colours from one kind of pigment molecule.

Optional - show students molecule models of red and blue anthocyanin molecules (I used the cyanidin molecule, which is the red pigment in dark red roses), and challenge them to find the difference between them. (Clue: look at the white hydrogen atoms.) One particular hydrogen atom on the cyanidin molecule is present in the acidic version of the molecule (which is red) and missing in the basic version (which is blue). Depending on the amount of acid or base, there is a different ratio of red and blue cyanidin molecules, which gives rise to the range of red-purple-blue colours.

You may have also made green petal juice. This is when, in base, one kind of pigment molecule (anthocyanin) turns blue and another pigment molecule (anthoxanthin) changes from white to yellow. When the yellow mixes with the blue anthocyanin, green results. If the colour changes are grouped on the board as they are gathered, the two kinds of pigment molecules can be seen separately and as mixtures in some kinds of flower petals.
Not all flower pigment molecules change with the amount of acid or base e.g. the yellow of tulips and other flowers. Pigment molecules mix and match together to make all the different flower colors that we see.

Students freely experimenting may also notice that bubbles sometimes form. If acid and base are added to the same well of the tray they chemically react to make CO2 gas (see baking soda chemistry).

Flowers attracting pollinators focus
By varying acidic/basic conditions in their petals, the anthocyanin molecules in flower petals make red, blue or purple colours. By mixing the anthocyanins with other colour molecules (e.g. yellow, orange), flowers can display a wide variety of colours. Different pollinators are attracted to different coloured flowers. See the flowers and insect pollinators activity. Some flowers even change colour as they age (e.g. the forget-me-not), indicating to pollinators they are past pollination time, so the pollinator will move to another flower which is ready for pollination.

Physical and Chemical Changes focus
Discuss how tearing and crushing the petal is a physical change. The shape has changed but it is still the same molecules of dye and water. Crushing the petal in water is a physical change: the dye moves from the petal into the water, but the molecules stay the same.
Ask students to look for chemical changes when they add acid and base to petals. Chemical changes are shown by: a change in colour, a change in smell or appearance of a gas. Students should find colour changes as the petals change colour in acid and base, as well as the appearance of a gas (when baking soda solution and vinegar are mixed together).

(Note: text marked with [] was omitted for primary students).

I’m going to talk about us - how we grew from a tiny dot. And about why do we all look different from each other. And why we all look like people, and not a cat or a tree.

(show image of DNA on overhead)
This stuff is the answer to all of these questions: DNA is the most amazing thing. You might have seen pictures of it before. There is DNA in every cell of our body - it is a spiral molecule. And it is the instructions to make our body. This is a billion times bigger than real DNA.

We all started as a tiny single cell. The DNA in that cell has instructions to tell the cell to [divide into more cells, and the instructions to tell those cells which to become back which to become front, then where to make a head, where to make a heart or an eye. Gradually, as more and more instructions are read, a human body] grows and develops into you.

(Show a petri dish of my DNA on overhead)
This is my DNA. I got from the cheek cells in my mouth. In that DNA is the instructions to make my body - my eye colour, my hair colour, why I need to wear glasses, even some of my personality. Your DNA looks the same on the outside, but when scientists look up close they see small differences between different peoples’ DNA. Those tiny differences are what make us all look different.
(Show image of DNA again and point out letters)

(Show hefty book of Shakespere)
If a book is the DNA instructions for a person, we need 100 of these books. Tiny parts of DNA are different between us, like spelling changes in words. That is why we look different. Most of our DNA instructions are the same, as we are all people, but those tiny changes are what makes us all look different.

A few of you have a change in your DNA that none of the rest of us have. Who here has red hair? I can show you exactly what change in the DNA makes your hair this colour - scientists have figured this out.
(Show sequence with one letter change in hair colour gene).
This is a part of a page in our book of DNA instructions. Can you find the one letter that is written in red? The rest of us have a G here. The redheads have a C here. This change in the instructions changes the colour of hair.

Theo has a change in his DNA that none of the rest of us has. Theo has a change to the instructions that tells the body how to grow. This change means that Theo is growing more slowly than the rest of us. Other people with the same DNA change as Theo also grow slowly and look like him. Only one in 10,000 people have the same DNA change as Theo.

Who has blue eyes? Another part of the DNA instruction book determines eye colour. You all have the same DNA letters in that part of the instructions and the rest of us have different instructions.

The only people that have the exact same DNA instructions are identical twins. Any identical twins here?

Everything about the way we look - our hair colour, how we develop, our eye colour, our height, also how we move, see, hear, eat, and talk is built from our DNA instructions. We are so complicated, that we can even think about ourselves thinking. It is absolutely mind boggling how complicated we are - and much of that complexity is built up from the instructions in our DNA. Life comes from this amazing molecule, DNA.

I've talked about our bodies and how we look like we do, but it's only part of the story. Now Theo's Dad will continue the story.

What about the bacteria in the starter mix?
It is a kind of bacteria that makes lactic acid from sugar. They eat sugar and make lactic acid.
Here are model molecules to show what happens. The bacteria eats the sugar and breaks it into this.
The acid made by the bacteria helps keep other bacteria and yeast away as they don’t like acid.
It also helps make more holes in the cake.

Lets do an activity to see what the lactic acid made by the bacteria does.
Put a scoop of baking soda in a cup.
One of the ingredients of the cake mixture was baking soda.
Pick up a cup of vinegar.
This is a acid like the acid made by the bacteria in the starter mixture.
Pick up your cup of baking soda, and a cup of vinegar. Keep them separate and take them back to your desk.
Once we are all sat down.... Just as in the cake recipe, with acid from the bacteria baking soda, pour the acid into the baking soda.
What happens (get bubbles).
The acid from the bacteria (which might make it smell as though the starter is off) and the baking soda we add to the recipe make gas bubbles. These get trapped in the batter and make the holes in the cake.