ingridscience

Giant bubbles outside as demonstration.
Students make frame from a loop of string and two straws.
Make own bubbles.
Watch the changing shape and colours in the giant bubbles.

The colours are due to the structure of the bubble skin - two layers of molecules, which separate white light into its colours.

Make a foam drink, by adding air bubbles to milk.

Give students a cup of milk and a straw (and a squirt of flavouring).
Ask them to blow bubbles in their drink to make foam, then drink their "milkshake".

The bubbles are air blown into the drink, which are stabilized by components in milk.

Optional: do the foam molecule test on the component molecules of milkshake (protein, fat, sugar), to find out which ones make the foam. (The fat and protein.)

The foam is a kind of mixture called a colloid.
See the attachment for other kinds of colloids and mixtures.

Pour your bubble mix onto a black plate (about 20ml each). Use a straw to blow as large a bubble as possible (blow long and slow).
Look at the colours. Hold a sheet of white paper behind the plate at an angle to see more colours.
Why are they there? Made by the layers of soap molecules - refer drawing of structure to explain. (Light is made of many colours - when white light bounces of the first layer and the second layer the colours interact with each other and some colours are taken away leaving the others - called interference). So see all the colours in white light.

The colours in oil or on a CD are formed in the same way. Rainbow colours and colours from a prism are also formed from the separation of white light into its component colours, but by a different mechanism (refraction).

Are bubbles always round? What happens if you make another shape with your pipecleaner? Make two shapes. (Optional: add straw for handle.)
Blow and watch others in your group - look for bubbles that are not round. Let me know if you see one.

Why are bubble always round? Show structure of a bubble (layer of water molecules trapped between two layers of soap molecules). The soap molecules can move around, so can the water molecules - they are elastic. They move until find most stable shape: for one bubble this is a sphere.

Who’s blown bubbles before? We’ll make our own bubble mix today, then you can see what the basic ingredients are. This is the recipe that science world uses.
Smell the tube. What is in it? Baby shampoo. It’s soap. Soap makes bubbles.
We’ll add the same amount of water. What number do we add water to?
Mix it with the stick, then put the lid on, and gently invert to mix. Do not shake.

Now we have our bubble mix.
The simplest bubble blower is a straw.
Students dip their straw in bubble mix, take it out, and blow bubbles (they will generally be quite small).
Challenge: How can you make lots of small bubbles, or one large bubble. Control how you breathe.
While you are blowing, figure out what each bubble actually is. (Air inside a layer of soap.)
The soap molecules can move around within their layer, to settle at the most stable shape: a sphere.
If you make many small air bubbles that pile up, you make a foam (a kind of colloid mixture that is bubbles of gas trapped in a liquid (the soap mix)).

Look at the commercial bubble blower. What is the difference between theirs and ours that might make more bubbles? It has more places for the bubble mix to sit - so can make bigger bubbles.
Try making a pipecleaner blower, which should hold more mix: make a loop at the end of a pipcleaner. (Optional: push the straw on the long end for a handle.)
You should be able to make more and/or bigger bubbles because the pipecleaner fuzz holds more bubble mix.

Students are instructed to search for the items on their bingo card within a designated area.
Students call Bingo! when they have found all the items on their sheet.

Students look closely at sand and find the colours in it. They can tape a sample in their notebook, use a magnifier to look at the grains closely, and list the colours that they find.

Students rub a smear of mud onto their worksheet, allow it to dry for a few seconds, then add a piece of tape over it.
They use a magnifier to look at the sample closely, then estimate how many grains of mud could fit into a grain of sand.
See particle size chart at: wikipedia.org/wiki/Particle_size_(grain_size)

Discussion that sand (and mud) are made from rocks broken up by the waves.
Students look for larger rocks of the same colour on the beach, that may have been broken into sand/mud. Teacher can name them: basalt is black (igneous rock), granite is speckled and can be broken into its mineral components: quartz (clear/white), feldspar (pink), mica (shiny flat black).

Students can look for other debris in sand, especially parts of shells.
Discussion that the shells of the animals become sand as they are broken up by the waves.
Students can sieve sand to find more broken shell pieces, and tape them in their notebook.

Students are shown a marine snail egg case (e.g. knobbed whelk egg case containing tiny shells), found washed up on a beach (information and images).
An adult cuts baby shells out of the egg case. One shell is put in each student’s box magnifier.
Discussion of the shell shape: spiral, unlike the clams (and mussels) we have looked at before.
Students draw the spiral shell, filling a page of their notebook, to be as large as an adult shell. Tape the baby shell next to the adult, to compare the enormous size difference between baby and adult shells of this type.

Students each find a piece of rockweed. Discuss what it is, where it grows, and that it is an alga (not a plant).
Students look closely at the parts of the rockweed, draw it in their notebooks (draw around a small piece), then label the parts: holdfast, bladders and blades.

Optional with older students: predict of what the parts of the seaweed might be for (younger students just guess, and then feel bad if they are "wrong" distracting from the activity).
Test the function of each part of the seaweed by tearing the rockweed into pieces: pieces of the blade or a bladder on its own, then see if each float in a tray of water.
The blades should sink, and the bladders float (unless the air has been popped out of them). Do many pieces until a pattern is seen.

Discussion of the parts.
Bladders: they keep the tips of the seaweed floating up in the water, to maximally expose all parts of the seaweed to sunlight. The bladders can be torn open to find the gas bubbles among the jelly that make it float.
Holdfast: it keeps the seaweed anchored to a rock, so that it is not washed ashore.
Blades: wide to catch sunlight for photosynthesis.

Younger students can use their hands to show how rockweed grows: a balled fist is a rock, and use the other hand on top with the fingers ("blades") spreading upwards; the fingernails represent the "bladders".

Beach hoppers live under dried seaweed, and can be used for further discussion if there is time (information and images of beach hoppers, 6th image down).