introduction these materials consist in four … · introduction these materials consist in four...

TEACHER’S NOTES

Roser Nebot IES Manuel Blancafort (La Garriga)

INTRODUCTION

These materials consist in four experiment centred activities and an introductory activity to learn the laboratory items vocabulary. The activities are:

� Laboratory based teaching–learning sequences. TLS.

� Context Based Learning (CBL). Each practice is related to reality with simulations and internet research to promote and enhance active student learning and integration of knowledge. The students have a say in how they learn.

� Students work in small groups under the guidance of the teacher (social constructivism).

The teacher is not in front of the activity but leads the way. It is important to stop from time to time to do a plenary to check if the students understand what they are doing or if there is a problem. This way the knowledge is built with interaction among students and between the teacher and the students. For them to report in English it is important to give frames such as substitution tables and cues.

� In the teaching sequence the students have to follow instruction accurately, but they also

have to work in little projects. When they are used to this way of teaching-learning it is time to work with Problem posing approach, working in projects in which they can develop autonomy.

TEACHER’S NOTES


LABORATORY GLASWARE In the first activity students are asked to use observation to classify the laboratory glassware. It is an easy task with continuous feed-back to and from the teacher and a final feed-back session as a whole class in the plenary. In the next activity the students have to show that they have understood the use of dicotomic keys by means of changing them to include a new item. Firstly they have some scaffolding (a frame) to support their thinking about the characteristics of this new object. Next they have to compare it to the objects they have already classified and introduce the new object into the dicotomic key. As the Kitasato is a flask with a broad neck, in the second part of the 4th dicotomic key, instead of saying Erlenmeier or conical flask it has to say: Go to 6. And they have to create the sixth dicotomic key to classify the Erlenmeier and Kitasato flasks. They have to add the Kitasato too to the classification diagram and draw it. They previously had to draw the other items they had classified. The final activities are language scaffolding activities to help students to learn the names of laboratory items in an easy way. The exercises are introductory and in general involve low-level thinking, but have powerful language scaffolding that will be useful when the students have to look for the necessary material in the practical classes.

TEACHER’S NOTES


THE THERMOCLINE In the first activity students predict and later observe the different speeds of dispersion of the same solute (a colouring) depending on water temperature. To explain what has happened they rely on kinetic-molecular theory. Cold water Hot water It is useful to complement the activity with a role-play in which some students represent the molecular distribution of cold water by clustering together and others represent hot water by moving apart. In the hot water role-play it is also interesting that some students try to escape while others try to catch them, as happens to the molecules in very hot water. Students are then introduced to the study of the concept of density that will be dealt with more deeply in the iceberg activity. In the thermocline simulation students apply what they have learnt to interpret a natural phenomenon. There is the possibility of colouring the hot water before adding it to the cold water, but when it is added drop by drop it is easier to observe the barrier produced by the thermocline, as the drops collide with it and rebound, making it very visual. Sometimes the drops traverse the thermocline boundary and form “warm currents” within the cold water. Students have to be very careful when adding hot water on top of cold water. They have to pour it very slowly. Before continuing it is important to state that they have just simulated the situation of the sea in front of Perú during the El Niño phenomenon. In the following webs there are different definitions of thermocline:

http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/thermocline.rxml http://www.esr.org/outreach/glossary/thermocline.html

TEACHER’S NOTES


http://www.broadwaters.fsnet.co.uk/thermocl.htm

http://www.britannica.com/eb/article-9072079/thermocline It is interesting to comment on the differences between lake and sea thermoclines, and how thermoclines change during the year. The students could carry out a research on the internet as homework. Here there are some websites where you can find information. http://www.rmbel.info/Reports/Static/Stratification.aspx# http://www.lei-extras.com/tips/sonartut/thermocline5.gif

http://www.agagroup.org.uk/images/ThermoclineB4.jpg

http://serc.carleton.edu/details/images/1954.html

TEACHER’S NOTES


These are good links if you want to work graphic interpretation.

www.coexploration.org/.../thermocline_graph.html

http://www.windows.ucar.edu/tour/link=/earth/Water/temp.html&edu=elem

TEACHER’S NOTES


ENSO phenomenon: El Niño, La Niña and the Normal situation.

There are a lot of websites dedicated to the ENSO phenomenon. As well as those indicated in the students’ work-sheets, you can find information too at: http://www.nationalgeographic.com/elnino/mainpage2.html There is one edition of National Geographic dedicated to this theme that is very clear and explains very well the climatic implications in Eastern, Western and Central pacific. http://www.ucar.edu/communications/factsheets/elnino/ By relating the practical class to a real phenomenon with curious names and worldwide effects the students get very interested in the activity. If there is an article in the newspaper related to the phenomenon while learning about it, it would be advisable to analyse and comment it to contextualise more the concepts studied in the lesson. To finish there is the expert’s group work in which each group has to explain one of the situations with the help of a Power Point presentation. A powerful tool is the auto and coevaluation of the activity preceded by the clear statement of the items that will be used by the teacher to evaluate the student’s work. If the ambience is good a very interesting and amusing way of finishing the didactical sequence is by making students represent in groups the three situations: El Niño, La Niña and the Normal situation. They can even dress in blue or red depending on which water they represent.

TEACHER’S NOTES


ICEBERGS

The first activity is an introductory activity about The Titanic and its shipwreck to capture their attention and enhance their curiosity towards icebergs. There is a head and tails activity and some questions to help them understand the text. The activity finishes with the question: How could an iceberg destroy such a huge ship? This question, that they are not probably prepared to answer, will be asked again at the end of the didactical sequence. Next are some questions to explore the students’ previous knowledge about icebergs, which will be asked again later in the activity. The part when they learn to detect whether water is salty or not without trying it is a preparatory activity to allow them to discover later that icepacks and icebergs are made of fresh water. I think it is important to explain that icepacks are formed from sea water but icebergs come from inland ice. There are two sets of questions that are studied in a parallel way: � The fact that the maximum water density is acquired at about 4 ºC, and that this allows ice to

float on water. � The fact that this is an anomalous behaviour not shared by other molecules.

http://www.rmbel.info/Reports/Static/Stratification.aspx#

TEACHER’S NOTES


A special comment on the application exercise:

What will happen when the ice you see in the picture (polar bears on an iceberg) melts? Tick the ideas that are correct.

• The polar bears will get wet • The level of the sea will increase • The level of the sea will diminish • The level of the sea will not change • The changes in the sea level will depend on where the ice came from

In this exercise students have to arrive to the conclusion in the plenary that the best answer is the last one, because the increase or decrease in volume will depend on the origin of the ice. If the ice comes from the continent, it will increase the ocean level when it melts. But if it comes from ice that was formed in the sea, then if it melts the ocean level will remain the same. This activity is very high-level thinking and so has to be carried out only by the more able students in the scientific area or by older students. You can complement it by making the students design an experiment to back up their ideas. You can add two ice cubes to a beaker with water and mark the level and you can put water on a beaker, mark the water level, and then add two ice cubes. You will see that the water level doesn’t change in the first beaker as the ice melts (this would be the case of an icepack made of sea water’s melting), but that the water level in the second case increases (that would be the case of an iceberg coming from land’s melting). To finish the students have to compare what happened in the experiments with their predictions and answer the question: How could an iceberg destroy such a huge ship as Titanic? And now they are prepared to answer it correctly with solid scientific argumentation. And to trigger the curiosity a little bit more they are asked a new and final question: Why is it so strange that there was an iceberg on the Titanic’s route? And they are given a site to find the answer. Two possible interesting homework exercises would be:

� Investigating on the internet about Greenland or the Antarctic Ice Thaw and writing a report.

http://www.thewe.cc/thewei/_/images_2/bbc/greenland_heatin

g.jpe

TEACHER’S NOTES


http://www.theoildrum.com/uploads/12/rignot_greenland_extrap.jpg

� Asking them: in a final plenary to share their ideas.

Why it is important that lakes in cold areas develop an ice cover? First thinking about it all together in class, later at home and again in class. To help them to answer the following website is very interesting.

http://www.rmbel.info/Reports/Static/Stratification.aspx#

It is important that they understand that the ice cover protects the ecosystem in the water below by keeping the temperature there above freezing point.

http://staffwww.fullcoll.edu/tmorris/elements_of_ecology/images/l

ake_temp_profile.jpg

TEACHER’S NOTES


The exercise can be related to what they learnt in The thermocline and El Niño lesson.

TEACHER’S NOTES


DEW POINT, CLOUDS AND FOG

In the activities related with dew formation it is very important that the students realise that dew point depends on air humidity. And also that it is constant if humidity and pressure don’t change. There are some complementary activities based on kinetic-molecular theory to help them understand why dew points vary with air humidity and temperature. The practical activity convection helps to understand the relationship between changes in temperature (cinetical energy) and changes in density, relating them to kinetic-molecular theory. It is important that the water poured into the glass jar has to be warm but not steaming. Shining the flashlight while the convection is happening really helps students to see it better. With the other practical activity ‘Clouds, fog and smog in a bottle’ the importance of condensation nuclei in the formation of clouds, fog and smog is highlighted . The Schin-chan’s Cartoon helps to relate condensation to everyday life and the activities related with fog and smog help the students to relate what they have just seen to important global issues such as industrial contamination. As homework they could study the different types of cloud and the relationship between the way they are formed and their shapes. It also would be a good idea to compare different places in the world with different levels of contamination and a particular place now and some years ago and investigate about what has happened with air pollution in a similar way that they do with Peking. Both activities are quick and the same group can do both set-ups.

TEACHER’S NOTES


Here there are two images and a web page that can be useful.

• Dew point

http://www.ace.mmu.ac.uk/Resources/Teaching_Packs/Key_Stage_4/Weather_Climate/images/04c.jpg

• Types of clouds

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml http://en.wikipedia.org/wiki/Cloud http://vortex.plymouth.edu/clouds.html/ apollo.lsc.vsc.edu/.../tut_folder/nick_tutorial/

http://www.bbc.co.uk/weather/weatherwise/images/gr_ff_pop_cloud_types_large.jpg

TEACHER’S NOTES


WATER CYCLE

The lesson begins with an introductory activity to see what the students know about the water cycle and to focus on what they are going to work on. The activity has the underlined purpose to make them think about the underground water, which is frequently forgotten in the activities and drawings related to water cycle. Then there are the instructions to build the water cycle simulation. It is important to read them before all together to test that everybody has understood what has to be done. To complement the study of evapotranspiration it is a good idea to do the parallel experiment taking a bigger plant in a pot and covering it with a plastic bag tied around the stem, leaving the soil exposed to air. It is interesting to do it with four or more plants and leave some of them in the shadow and some in the sun. Sometimes it is very difficult to see the water droplets in the small plant that is inside the set-up. As you have seen the origin of condensation is thoroughly discussed in the activities so that the students understand that evapotranspiration comes from the addition of transpiration (plants) to evaporation. By making the students label the underground water level and observe how water percolate through the holes in the aquifer we are making them aware that underground water doesn’t circulate in rivers inside underground tunnels, but trough the interconnected holes and crevices. The overexploitation, contamination and salinisation activities help to understand how humans affect nature and how the effects are not the same in different parts of the world.

TEACHER’S NOTES


To finish there are different exercises to review, summarize and complement all that has been learnt through the lesson. This is a practical experience that gives the students a much more holistic approach to the water cycle than the typical following the cycle of a water drop. To criticize the fact that many times underground water is forgotten, as a homework they can surf the next to find water cycle’s drawings and animations that don’t show them, as it happens on the images below. You could bring to the class some books where it happens the same and some others were underground water is seen, but there are not depicted the rocks that contain them. http://tre.ngfl.gov.uk/server.php?request=cmVzb3VyY2UuZnVsbHZpZXc%3D&resourceId=12592 (Look at the bottom of the page) http://www.ace.mmu.ac.uk/Resources/Teaching_Packs/Key_Stage_4/Weather_Climate/04.html

http://www.dnr.state.wi.us/org/caer/ce/eek/earth/groundwater/images/groundwater.gif

http://www.metoffice.gov.uk/education/images/water_cycle.jpghttp://www.metoffice.gov.uk/education/images/water_cycle.jpg

TEACHER’S NOTES


http://www.enchantedlearning.com/wgifs/Watercycle.GIF

http://www.marietta.edu/~biol/102/wcycle.gifhttp://www.marietta.edu/~biol/102/wcycle.gif

TEACHER’S NOTES


� And the last question is: do you think it rains over the sea?

www.uen.org/.../uploads/5446_a_duck.jpg

The idea is to make them realize that in the water cycle representations it never rains over the sea and that to adjust to what really happens there should be also rain over the oceans and seas.

TEACHER’S NOTES


introduction these materials consist in four … · introduction these materials consist in four...

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