ingridscience

What might affect the direction that roots grow?
(Students might suggest water, darkness....)

Put some beans in a jar at different angles to test which way the root and shoot grows each time:
Make a ring of coffee filters paper towels inside the jar, and stuff the centre with more paper towels.
Add water to the paper towels until they are wet and there is a small puddle at the bottom of the jar.
Push the bean seeds between the coffee filter ring and the glass jar wall, to hold them in place, each at a different angle, spread out around the jar.

One week later:
What can we conclude about something other than water and air (and darkness) that seed germination is sensitive to? Gravity.
Which way up should we plant a seed? (Doesn’t matter)

Results:
The roots always grow downwards, then the shoot upwards.
The seeds are uniformly wet and exposed to light, so they use gravity to determine which way to grow.

Plants come from seeds. Why don’t these seeds turn into plants? They need certain conditions to germinate.
We’ll test what seeds need to grow into plants.

Work in table groups to set up 3 experiments:
1. seeds on wet paper towel (get water and air and light) - crunch up a paper towel in the bottom of the tub, wet it, then lay over a folded paper towel to make a damp, flat surface for the seeds. Layer some saran wrap over the top with small holes punched in it, to let in the light, but keep water from evaporating away as fast.
2. dry seeds in tub (get air and light, no water)
3. seeds under water (get water and light, no air) - put seeds in a tub filled with water.
4. seeds on wet paper towel wrapped in foil (get water and air, no light) - set up as 1 then wrap in foil to keep the light out. Open each day briefly to let plenty of oxygen in.
5+ Add other variables that students come up with that are dooable e.g. adding soil (the seeds have water and air, but no light if they are buried in the soil). e.g. keeping the seeds cold e.g. damaging the seeds (mimic damage by pests by puncturing or cutting the seeds)

Optional: make predictions about what will happen. Doesn’t matter whether you are right or wrong. It just gets you thinking about it.

Leave tubs in a warm spot for a week. Make sure the wet conditions stay wet - check at least once a day. The seeds under water will need to have their water changed, so that mould growth does not take over.

One week to 10 days later:
Did you have a look during the week at your seeds? What did you notice? Look at all your experiment dishes. What do you see?
The long white thing coming out of the seed is the root, and comes first. Then the shoot, which is green, and might have distinct leaves.
Record average root and shoot length for each of the tubs. Combine results into a class chart.

Expected results:
The seeds in the dark with water and oxygen grew the most in a week - they had long roots and many had shoots too.
The seeds with water in the light grew the next best. They had roots, but they had turned brown at the ends and very few had shoots.
The seeds with water but no oxygen grew the next best. They had split open and had sent out a root, but it stopped growing pretty quickly.
The seeds with no water did not grow at all.
Conclude as a class what seeds need to germinate (water, air, darkness).

Possible additional variables and results:
Seeds with soil grow well (they have darkness, wet, oxygen and also nutrients from the soil).
Seeds in the cold do not grow well (discuss: seed germination is triggered by the warmth of spring).
Seeds that are damaged sometimes germinate (discuss: probably depending on whether the embryo is been damaged or just the cotyledons).

Optional continuation of experiment:
Continue the experiment with the plants that are growing OK (should be the seeds in the darkness either on the wet paper towels or in soil), to find out what the plants need once they have germinated.
Results should show that plants need light when the leaves appear. With no light, the leaves are present but pale green.

We eat all parts of the plant, but have bred plants so that the part we eat is larger and tastier.
If necessary, review the names of the parts of the plant (see image and worksheet).

On the worksheet, first connect each label with the plant part.
For each plant on your table/in the garden, identify it, then add its name to the box labelled with the part of the plant that we eat. Some plants may go in two boxes.
Discuss with your group if you are not sure. Optional: the students can open the plants if you need to look more closely.
If you get done early, think of more plant parts that you eat to add to each box.

roots=carrot, parsnip, onion
stem=celery
leaves=spinach, lettuce
flowers=broccoli
fruit=red pepper, tomato, apple

Review what a fruit is, and how it is formed from a fertilized flower. Use the image from "The Reason for a Flower" book, or another image that shows the transition from a flower to a developing fruit.

Time lapse of a pear flowers becoming fruit: https://www.youtube.com/watch?v=SHHkmOh942A

Study a portrait in groups and find and list as many fruit, vegetables, flowers as possible.
Report back to class on what each group finds.

Add the whipping cream to each jar.
Students in a circle, shake the jar, then pass it on.
Shake until the cream is whipped (see first photo), then shake more to separate the fat and buttermilk (see second photo).
Pour out the buttermilk to taste.
Dump out the butter, add a little salt, and eat on bread or crackers.

For a lesson on states of matter, the students point out when they find a state during this activity, whether an ingredient or a new state from a reaction.
Discuss the changes in states of matter while making butter: start with a liquid (cream), which becomes a foamy solid (whipped cream), which then separates into a solid (butter) and a liquid (buttermilk).

For older students, work through the steps of how the molecules are arranged in the cream and butter.

For a lesson on mixtures, every step of this activity is a different type of colloid is formed:
Cream is an emulsion (drops of liquid fat in liquid water)
Whipped cream is a foam (air bubbles in the liquid cream)
Butter is a gel (liquid water droplets in solid fat)
See attached mixtures file for examples of other colloids, and other types of mixtures.

(Song used while shaking with younger students, to the tune of "Row, row, row your boat":
Shake, shake, shake the cream,
Shake it in a cup,
We are making butter now,
Then we'll eat it up)

For a lesson on states of matter, the students pointed out every time they found a different state during this activity, whether it is one of the ingredients or a new state made by a chemical reaction.

Make dough in groups of 3 or 4.
Teacher adds water to the bowl. Students add yeast, sugar and mix.
The yeast is a living thing and starts to eat the sugar.
Students add the salt, flour and mix.
Then use hands to knead the dough (stretch, fold and flatten, repeated).

Divide each dough ball into 3 or 4 pieces. Put a piece on each square of aluminum foil for each student.
The students knead some more, then mould into a shape (e.g. pretzel).

Talk about what is happening to the flour as it is kneaded: the flour has molecules in it that are made longer and longer as the dough is stretched, then folded over. They give the dough an elastic texture, that gives the finished bread the light texture.

Leave to rise for a few minutes - a gas is made by the ingredients that make the dough rise.
(During the wait another activity can be run. To isolate the ingredients that make gas do Yeast eats sugar and makes gas or test which ingredients make gas. To look at the chemistry that makes the bread rise, use molecule models to model the chemical reaction. See lesson plans for integrating the activities)

Review ingredients/chemical reaction of the bread rising:
What is yeast? A living thing. Breathes like us.
It eats sugar and releases gas bubbles into the dough.
The gas bubbles get stuck in the dough and makes it rise.

Put the bread in the oven:
Add name to each piece of foil.
Brush bread with egg and put in the preheated oven.
Bake at 350 degrees F for about 15 minutes, until brown on top. They may need turning/switching around in the oven.

While the bread is cooking, do another activity: make butter or use molecule models to show the chemical reaction happening between yeast and sugar. See the lesson plans for including these activities.

Before eating the bread, break it open to see the holes in it, made by the expanded gas bubbles in the dough.

Tape the black paper to the back of the jar to create a dark background. This will make the cloud more visible.
Fill a third of the jar with warm water. If condensation forms on the inside of the jar, tip it up to clear it off with the water.
Light a match, blow it out, wait for a second or two, then drop the smoking match into the jar.
Quickly put the bag of ice on top of the jar, so it forms a cold lid over the opening.
Water vapour rising from the warm water condenses onto the smoke particles, and is visible as swirling clouds.
Lifting the ice bag releases the cloud.

This activity is not too dramatic, but does replicate exactly how a cloud forms. See the dry ice cloud for more dramatic demonstration.