ingridscience

If this activity is to be conducted in a classroom, collect small rocks with barnacles attached, and store in the fridge overnight out of water. Also collect containers of sea water, one kept in the fridge, one at room temperature. Return the barnacles to the same beach after the experiment.

At a beach, ask students to find barnacles themselves. Point out the young and old barnacles, and the scar where a barnacle used to be.
Live barnacles can be gently touched to make them shut their shells tight.

Watch barnacles feeding:
With the barnacle rocks in a jar each, add sea water to them.
Watch and wait. The barnacles will first release a bubble of air, then gradually open up and start to feed.
Their head is down attached to the rock. Their legs (called "cirri" in a barnacle) point upwards and beat back and forth to catch tiny particles of food in the water.
See half way down this page for a diagram: https://seahistory.org/sea-history-for-kids/barnacles/
or this page http://courses.washington.edu/mareco07/students/nina/barnacleshome.html
Barnacles at the beach start filter feeding when the tide comes in, and close up when the tide goes out.
Video of barnacles feeding: https://www.youtube.com/watch?v=-dgmV-tyUek Slow motion at minute 3:10

If you add room temperature water to the jar, the barnacles will start feeding very rapidly, but will die if the water is too warm for too long (i.e. 18 C, or so).
If you add cooler water, the barnacles will last for longer, but may not start feeding as rapidly.

Optional, though quite subtle: compare beat rates of barnacles at different temperatures. Temperatures need to be around 8C and 18C to really see a difference, and it is hard to maintain the sea water at these temperatures in a hot classroom. Also, different barnacles inherently beat at different rates, so it is an overall effect to be noticed: at the lower temperature they are overall beating more slowly than at the higher temperature.

Use barnacles feeding as a demonstration of how animals are dependent on the tides. As the Moon rotates around the Earth it pulls on the oceans back and forth, and causes tides. Animals live by these tides, the shelled animals feeding when the water comes in and closing up when the tide goes out. The crows, other birds, and wolves in more remote areas, wait until the tide is out, to feed on the shelled animals.

Great article on the great variety of places that barnacles live, and their place in the food web: https://outlifeexpert.com/barnacles-decomposers/

Barnacle larvae can travel 85Km before they attach to a rock as adults. (https://www.journals.uchicago.edu/doi/10.1086/BBLv216n3p373)

Teacher or student helper adds seeds/grain to a large tray of water, to represent food particles floating in the seawater.
The teacher shows the class the mesh stuffed into the cup, representing the hairs inside the clams body.
The teacher/student helper scoops the cup through the water and food particles, representing the clam taking in water with a siphon.
The teacher/student helper pours the water out of the cup again, representing the water leaving the clam’s body by the siphon.
The teacher shows the students the seeds/grain stuck in the mesh, representing the food particles stuck in the hairs in the clams body.

More information on filter feeding for the teacher at http://nathistoc.bio.uci.edu/Filter%20feeders.htm

Optional: precede this activity with finding clams on a beach.

The clam has a muscle that keeps the shell tightly closed. The frozen clams will open up slightly, revealing this white adductor muscle.
Cut the muscle or simply pull open the clam to look at the internal organs.
Give students a photo of the inside of a clam to help them find the parts. (Photograph of the inside of a clam web archived at: http://web.archive.org/web/20070630042552/http://iweb.tntech.edu/mcapri…)
Clams and humans are both animals, but they are a mollusc and we are a mammal, so we might expect that some body parts are the same and some are different.
Students find each organ in the clam. The function of each part is discussed as they find them, or after all parts are found..
Optional: use the attached worksheet to compare the clam's body parts with ours.
1. The clam SHELL protects the clam. It is its shelter. We do not carry our shelter with us.
2. The MANTLE makes the shell. We do not have a mantle, as we do not have a shell.
3. The clam FOOT helps the clam dig into the sand. We move with our FEET too.
4. The clam GILLS take oxygen from the water (like fish). We have LUNGS for taking in oxygen. (Students may need a toothpick to gently lift up the gills to see them properly).
5. One of the clam SIPHONS sucks in water. Tiny food particles in the water get stuck in tiny hairs on the gills. Then the food gets washed towards the clam's mouth inside the body. The water goes back out the other siphon. We eat with our MOUTH. (Students may need to straighten out the siphons with a toothpick to see them properly.)

Note: a mussel has similar parts, but they are arranged a little differently. See http://faculty.orangecoastcollege.edu/mperkins/zoo-review/clam-mussel/c…

Video on restoration of clam gardens: https://www.youtube.com/watch?v=22Nytmxw2Z8

Hand each student a clam. Questions for discussion:
1. Close your eyes, and describe what you feel.
2. Is a plant or an animal? Do you know what animal it is? Where have you seen one before?
3. Point out that this clam is not alive.
4. You are an animal. Does it look like you? In what ways is it different? (This clam is a mollusc, an animal with a shell. You are a mammal).
5. What does the shell do? Discuss how the shell protects the clam from predators.

Ask students to compare their clam with the other sized empty clam shells on their desks.
Questions for discussion:
1. Which is the oldest shell and which is the youngest? How do you know?
2. Shells get larger as the animal inside them grows. The shell grows to fit the body.
3. Where is the new shell added? (on the outer edge - notice that this edge is soft).

It is a rocket powered by a chemical reaction.
Baking soda and vinegar react to make gas, which is trapped in the corked bottle. When the gas pressure is great enough to push the cork out, the rocket flies up in the air.

Pour 200ml vinegar into the bottle (if 1L; use half cup vinegar for a 710ml bottle).
Add a couple of teaspoons of baking soda to the tissue, and roll it up like a burrito, so the baking soda does not fall out and the package is narrow enough to fit through the mouth of the bottle.
Students can do these steps.

Make sure that you are away from the students, or with only a pair of students invited to come with their materials to the launch pad.
Students watch while the adult pushes the baking soda package into the bottle, corks the bottle, shakes the bottle once, then stands it up for take off.
Run away from the launch pad to a safe distance (30-50m). Even if it takes a little time, the tissue will disintegrate to mix the baking soda into the vinegar, the gas released will build up enough pressure to push the cork out, and shoot the rocket high into the air.
If you think gas is escaping more slowly (around the side of the cork, for example) and the rocket will not fly, kick it over with your foot before reaching down to take it apart (so the rocket does not go off in your face), and reset it.

A rocket nicely demonstrates Newton's 3rd Law - for every action there is an equal and opposite reaction. The gas and liquid shooting downwards out of the bottle (the 'action') pushes on the bottle ('reaction') sending it upwards.

For a dramatic demonstration of Newton's 2nd Law, set the bottle right-side-up for take off (with the cork pointing upwards), making sure there is a mound of gravel or something around the base of the bottle so that it will not tip over. With the same amount of baking soda and vinegar, the cork flies way higher than the bottle (be careful with set up - the cork shoots out of the bottle really fast). With the same force, the smaller mass of the cork accelerates more than the larger mass of the bottle.

With older students, model the chemical reaction that powers the rocket:
Give each student a model of HCO3 (baking soda) and H (the atom that makes vinegar acidic). We started with these in the rocket.
The baking soda and vinegar molecules react and rearrange to make two new molecules. Ask students to figure out what these molecules are, giving them the hint that one of them is water.
The products of the reaction are water (H2O) and carbon dioxide (CO2).
Carbon dioxide is a gas, and as more and more of it is made by the chemical reaction, the gas builds up in pressure until it blows the cork out of the bottle.
Once the cork is released, the gas can escape by shooting out of the bottom of the rocket. This force propels the rocket upwards.

A rocket that goes to space acts on the same principal of action and reaction: the exhaust is expelled out of the back of the rocket, and this force is countered by a force on the rocket that propels it upwards.

Purchase molecule models online at Indigo Instruments https://www.indigoinstruments.com

This activity on its own is a full lesson length.

Introduction:
Do you ever cook or help to cook at home? There is a lot of science in cooking - all that mixing and heating - lots of chemistry and chemical changes going on. We’ll make scones today and investigate the chemistry happening in our recipe. And then we get to eat our experiment!

Recipe for scones on the board:
1 cup flour
1 teaspoon baking powder
1/4 teaspoon baking soda
1/8 teaspoon salt
2 tablespoons melted butter
1/2 cup buttermilk
Mix into a ball, and divide into four pieces.
Bake at 400F for 15-20 mins until brown

Before starting, review or remind students how to measure accurately: take a scoop of the ingredient, then pass a finger over the top of the measure so that the ingredient fills the spoon but is not overflowing.

Students take turns to add the dry ingredients (baking powder, baking soda, salt) from the tubs on the table. The teacher circulates with a bag of flour and cup measure for this ingredient. Mix all dry ingredients together with the spoon.
Then the teacher circulates to add, or help add, the wet ingredients (melted butter and buttermilk).
Students mix all ingredients with the spoon, then use their hands to shape the batter into 4 scones.
Put on the baking tray, or on pieces of foil with the students' names.
Bake in the oven, keeping watch after 15 mins, and remove when the scones are browned on the top.

While the scones are baking, test for why the scones rise:
Tell students that in the oven some of these ingredients chemically react to make a gas. The gas bubbles push the scone up to make it rise, and make it light and fluffy.
To figure out which ingredients make a gas, mix different combinations of ingredients together in the wells of the paint tray. Mix any combination you like from flour, baking powder, baking soda, salt and buttermilk, using the coffee stir sticks to scoop the dry ingredients and mix ingredients together. Use a new scoop each time, so that the ingredients do not get contaminated with each other. (We will not use the melted butter as it is messy, and it does not make a gas.) If you only choose dry ingredients, add a little water, to allow proper mixing, and to mimic the wet environment of the biscuit batter.

Optional, but recommended: students to fill out the worksheet so they can remember which combinations made the gas. Younger students can draw what they find.
If students are mixing many ingredients together each time, prompt them to only mix two ingredients, so that they can figure out the minimal ingredients are needed to make gas.

Results should show these results with the fewest ingredients: the baking powder and water makes gas; the (warmed) buttermilk and baking soda make a gas (though slower in making bubbles and less obvious).

If time with older students: the chemical reaction happening can be shown with molecule modeals (see resource for purchase of molecule models).
H (loose hydrogen atom, present in sour things) + HCO3 (baking soda) ---> H2O (water) + CO2 (carbon dioxide gas)

Hand out their scones.
Before they eat it, ask students to break their scone open, and look for the empty spaces, where the bubbles of gas were. The gas made by the ingredients mixing made bubbles, which got stuck in the dough and pushed it up to make it rise in the oven. Then the scone baked around them.

Show a real wood bug. Ask if students have seen them before in parks or gardens.
Ask what are the needs of an animal to stay alive? (food, water, shelter). Wood bugs have these needs too.
Class discussion of the needs of wood bugs (food, water and shelter), including where they like to hide, and what they like to eat. This discussion can be based on experiments done in class (see other activities in the lesson plan), and/or by a walk outdoors to find and observe wood bugs in their natural environment (wood bugs are easily found in the fall or spring under logs and rocks in gardens and forests).
Discussion ideas:
Wood bugs’ food is mostly rotting vegetation, so wood bugs are often found in the upper layer of a compost heap. Wood bugs are decomposers and eat dead plants (as well as some live ones). Decomposers are a crucial part of the cycle of life on earth.
Wood bugs need water to drink, as do all living things. They also need water in the air from which they obtain their oxygen (they do not breathe oxygen gas as we do). Wood bugs evolved from, and are closely related to, shrimp-like marine organisms. (The first woodlice were marine isopods which are thought to have colonised land in the Carboniferous period.) Like the ocean animals they are related to, they have gills - using them to extract oxygen from water. Because of this, they always need to be in a moist environment, and will die fast if they dry out.
For shelter, wood bugs like to live in moist dark places, such as under paving stones, rocks and chunks of rotting wood.
See reference for more information and different kinds of wood bugs: http://en.wikipedia.org/wiki/Woodbug. I believe I collected wood bugs from these three families: Oniscidae, Porcellionidae and Armadillidiidae (pill bugs, which roll into a ball).

Students build and maintain a habitat that satisfies the needs of wood bugs:
A layer of damp sand will keep the environment moist. Keep the sand damp (but not soggy - it is easy to make it too wet). Sprinkle drying sand with dechlorinated water (tap water let to sit for a couple of days).
A chunk of rotting wood provides shelter, as well as some food.
Food is vegetables (they love potato), also fresh leaves such as lettuce, and optionally some partway rotted leaves. Remove any food that becomes mouldy.
Store the habitat in the coolest area of the classroom.
Add wood bugs to the habitat from a walk, previous experiments, or from a collection made by the teacher in advance.

Students continue to take care of their wood bugs. If there are no small holes or gaps around the lid, take it off periodically to make sure there is enough oxygen in the container. Remove any food that mould grows on. The habitat needs to be moist but not soggy. A habitat can be kept for just a week, or several weeks. If kept for several weeks, babies may be born in the habitat. Do not pick up the wood bugs with fingers as they are very delicate. Use a paintbrush if you need to move them around.

After a week, look for evidence of the wood bugs eating (food with nibbles out of it), excreting (brown spots of faeces under the wood), growing (a shedded exoskeleton), having babies (new baby wood bugs; the eggs are too small to see with the naked eye).

When the habitat is ready to be dismantled (usually after a couple of weeks, maybe a month if the classroom is cool), they need to put back where they came from (choose a non-frosty day - spring and fall are when wood bugs are not hibernating, so the best time). Could be combined with a decomposer hunt activity.
Students use a paintbrush to flick the wood bugs from their habitat into a garden or sheltered spot.

Note: I am not doing this activity much any more - it is not good science.
The wood bugs in the food-choice dishes are too unsettled to actually be choosing the best food to eat.
Make a discussion instead about the role of wood bugs (vegetarians) and other decomposers - add these foods to the habitat and look for evidence of any of them being eaten.

Set-up prior to experiment: a large petri dish with fresh leaves, composted/rotten leaves (freeze lettuce for an hour to speed up decomposition) and potato slices. One dish per table group works well.
Wood bugs, one per student in closed containers kept moist with a layer of wet tissue.

Students tap their wood bug into the petri dish with the food choices, and put on the lid. Adults can help by gently pushing the wood bug with a paintbrush if necessary. Cover so that it is dark inside, and leave for a while.

Class discussion or another wood bug activity while the wood bugs to adjust to their new environment. Ideas to discuss: Talk about how different animals eat different things.
Optional prediction: students are asked to predict whether wood bugs would prefer the fresh salad leaves or the partway rotten leaves. For younger age groups, it is best if predictions are done anonymously: ask students to close their eyes, and vote by raising their hand. Class predictions are recorded on the board. A second vote of what the students might like to eat for their own dinner given the same choices lightens up the heaviness of predicting at this age, and gives some thought to how different animals might have different food preferences. (Note: I would recommend skipping this prediction step if the students have not already done a lot of hands-on science with careful observation and recording already. Accurately seeing and recording scientific phenomena is the first step to be mastered, before adding the complexity of thinking ahead and predicting).

At their desks, students are given a sticky note for each wood bug, then they can open the dishes. They look where each wood bug is found when they first open the dish (they are likely still moving around), and write each wood bug location on its own sticky note. Students may need help finding the last wood bugs if they are hidden under leaves.

Each student adds their sticky note to a class bar chart, above the correct food choice column. There is much variability in what food the wood bugs are found on (realistically because the wood bugs are more interested in escaping this foreign environment rather than choosing what food to eat).

The results of this activity can dictate what food to add to a classroom wood bug habitat. Even if no wood bugs were on potato, make sure that some is added to the habitat (wood bugs seem to potato it a lot).