Worksheets for Practicals

A worksheet is a good way to give instructions of how to carry out practical work safely and effectively. The students can refer to it whenever they are unsure of what to do next and they do not have to waste time copying out the method into their workbook – they can focus on the results and what they mean. However, one of the disadvantages of using worksheets containing detailed instructions is that students can end up following them passively, like a cookery recipe.

In view of this, I have started to develop worksheets for practicals that make extensive use of diagrams or photographs (images can be snipped from instructional videos on YouTube) and the minimum use of words. Furthermore, I include questions about what the students are doing and why they are doing it as discussion points at each stage of the process. Below is an example of one such worksheet that I made for an investigation of chlorophyll using paper chromatography.

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Plotting the Solar System on My Maps

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This is a fun activity for imparting the vastness of the solar system. Start by placing a football on the centre spot of the school football field or at the front gate etc. and informing your students that it represents the sun. If the circumference of the football is approximately 70 cm and the circumference of the sun is 4.3 million kilometres, how big would each of the planets in our solar system be (I like to provide a selection of everyday objects such as a tennis ball, apple, ping pong ball, and various marbles etc. for comparison) and how far up the road would they be located? Once the calculations have been made (this can be scaffolded by providing a conversion table or similar) ask the students to plot each planet, centered around the football, on Google My Maps.

Food Chains and Food Webs

The feeding relationships of the different organisms in an ecosystem can be shown most simply in a food chain. However, in most communities, animals will eat more than one type of organism and as such, a food web gives a more complete picture of exactly what eats what. Below are just a few ideas of how to teach both.

Wildlife documentaries

Wildlife documentaries contain lots of examples of real life (and often quite bloody) food chains and food webs, and asking the students to watch a few snippets before identifying the feeding relationships in each can prove a useful starting point to the lesson.

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Hanging mobiles

One common mistake when drawing food chains and food webs is for students to put the arrows the wrong way round and it is crucial that you emphasise that they point in the direction of energy flow up the chain. Asking students to construct food chain and food web hanging mobiles can help. You can download templates here or ask the students to make their own.

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Energy transfer

Energy transfer in food chains is inefficient; the amount of energy that is passed on is reduced at every step (trophic level). However, great care must be taken to ensure that you do not refer to the energy being lost, since energy can be neither created nor destroyed but rather is converted into some other form or store.

In food chains, much of the energy is transferred to the environment as heat during respiration but obviously some of it is also used by the organism (before it is eaten) in life processes such as movement and growth. Furthermore, not all of a food item may be ingested during feeding and, even if it is, not all parts will be digestible (e.g. lignin and cellulose).

A nice way to demonstrate energy transfer in a food chain is to pour coloured water between paper, plastic or styrofoam cups (each representing a trophic level) and reducing the volume of water transferred each time.

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Begin by pouring just 10% of the total volume of water in the jug (the sun) into the first cup (producer). This demonstrates that only about 10% of the sunlight that falls on a plant is used in photosynthesis since most of it is transmitted or reflected, and some of it is simply not the correct wavelength to be absorbed by the photosynthetic pigments in the leaf (only red or blue light is absorbed).

Next, pour roughly 10% of the water in the first cup into the second (primary consumer) and the remainder into another container labelled ‘Respiration (movement, warmth, growth) and excretion’ (do not pour the water down the sink as this will only reinforce the misconception that energy is lost). Repeat this process along the food chain.

By the time you reach the final consumer, only a couple of drops of water will remain. This is a good point in the learning to ask the students why food chains are usually restricted to just three or four trophic levels and why the number of organisms generally decreases along the chain.

Dinner at the Reef

This is a fun game from Arkive in which students learn about food chains in a marine environment, predator-prey relationships and the fine balance of an ecosystem. Although primarily aimed at 7 – 11 year olds it can also be used at Key Stage 3.

Interactive learning websites

There are now a large number of interactive learning websites offering simulations and simple ‘drag and drop’ style games for teaching younger students about food chains and food webs. Simply click on any of the images below to link.

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Stop Motion Animated Movies

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I have recently discovered this wonderful app for making stop motion animated movies on the iPad. It is free to download from the App Store but includes a number of in-app purchases such as sound effects and movie themes which you may wish to invest in. Students can simply draw a sequence of images on paper to photograph or build models using plasticine, Lego or pipe cleaners etc. Most recently, my AS students (who are currently studying a unit on immunity) animated clonal selection and expansion in B-lymphocytes (below), phagocytosis and the action of antibodies.

Hinge-Point Questions in Science

Hinge-point questions are diagnostic questions that are used at a particular point in a learning sequence when you need to check if your students are ready to move on and in which direction. Typically, hinge-point questions are multiple-choice and include wrong answers that challenge common student misconceptions. Critically, they are quick to answer and allow you to realistically view and interpret all students’ responses in 30 seconds or less.

Hinge-point questions should be used before you move from one key idea or learning intention to another, particularly if a solid understanding of the content before the hinge is a prerequisite for the next phase of learning. Apps such as Socrative, Kahoot and Plickers can all be used to provide instant feedback but mini-whiteboards or flashcards (below) also work well.

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Below are a couple of examples of hinge-point questions that I have used recently in my lessons. However, for more information, I highly recommend the free online course ‘Assessment for Learning in STEM Teaching’ offered by the National Stem Learning Centre via Future Learn.

Key Stage 3

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GCSE

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A Level Biology

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Teaching Artificial Selection

Artificial selection is the process by which humans select animals and plants for breeding because of their useful characteristics e.g. high crop yield in cereal crops and meat quantity and quality in beef cattle. Artificial selection has been practiced for thousands of years to produce varieties of animals and plants with increased economic importance. At GCSE, students may not only be required to define the process of artificial selection (or selective breeding as it is also known) but also state the similarities and differences between natural and artificial selection, and outline the steps involved in ‘improving’ crop plants and domesticated animals over many generations.

I would actually suggest introducing artificial selection before broaching (or revisiting) natural selection, as students often find it easier to grasp the concept of humans acting as the selective agent, purposively picking and choosing which individuals survive to breed, than the environment. There are also many examples of weird and wonderful selectively-bred plants and animals with which the students will already be familiar. Indeed, I tend to open the lesson with a short quiz in which I display photographs of sausage dogs, Merino sheep, Belgian blue cows etc., and ask the students to guess why they look the way that they do.

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Thinking Maps

However, once the students are familiar with both artificial and natural selection, it is useful to compare and contrast the two using a card sort activity, Venn diagram or double-bubble map. The students should identify that both processes require genetic variation and result in individuals with particular phenotypic traits (characteristics) surviving to breed and pass on their genes, while others do not. At this stage it may also be useful to reinforce the concept of evolution as being a change in frequency of particular alleles within a population over time and that, as such, evolution occurs through artificial as well as natural selection (one common misconception is that natural selection and evolution are one and the same).

Selective Breeding Game

This is a fun game in which the students, as farmers, aim to selectively breed sheep with both plentiful wool and high quality meat. It is a particularly effective activity for demonstrating that artificial selection occurs over successive generations and that the farmer does not actually create anything (the alleles for the favourable characteristics already exist) but simply decides which individuals can breed and which can not. The game is available to download for free here.

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Wolf and Dog Handraising Project

This is a BBC documentary entitled ‘The Secret Life of the Dog’ which features an overview of a fascinating experiment carried out by researchers at Eötvöus Loránd University in Hungary between 2001 – 2003. The aim of the experiment was to investigate whether the relationship between humans and domesticated dogs could be replicated with wolf cubs if they were treated like puppies and raised in the home. It makes for a fantastic discussion point about ‘nature and nurture’ by highlighting the fact that artificial selection can result in changes to an animal’s temperament as well as their appearance. The relevant section begins at 32 minutes in.

The Ethics of Artificial Selection

The danger of artificial selection is that that there may be too much inbreeding between closely related individuals. This can result in harmful recessive alleles being inherited alongside the desired genes, and an overall reduction in genetic variation. Indeed, many breeds of dog suffer from the effects of inbreeding e.g. elbow and hip dysplasia, epilepsy and heart disease (further information is available from the Kennel Club, among other sources). Asking students to consider the ethics of artificial selection, can prove an engaging topic for debate, if carefully structured.

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Tissue Fluid

As blood flows through capillaries within tissues, some of the plasma leaks out through gaps between the cells in the wall of the capillary, and seeps into the spaces between the cells of the tissues. This leaked plasma is known as tissue fluid.

Tissue fluid is almost identical in composition to blood plasma. However, it contains far fewer plasma proteins as most are simply too big to pass through the tiny holes in the capillary endothelium. Red blood cells are also too big so tissue fluid does not contain these, but some white blood cells can squeeze through and move freely between the tissue cells.

The tissue fluid leaves the capillaries under high pressure at the arterial end of capillary beds. In order to demonstrate this I use the following:

  • Five or six small balloons
  • Permanent marker pen
  • Large glass bowl
  • Glass jug
  • Water
  • Yellow food-colouring
  • Red beads
  • Rice
  • Pestle and mortar
  • Sieve

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Use the permanent marker pen to draw nuclei on the balloons and then place them into the glass bowl. The balloons represent the tissue cells. Fill the glass jug with water and add a drop or two of yellow food colouring (blood plasma). Throw in some red beads (red blood cells) and rice (plasma proteins) – grind up the rice in the pestle and mortar beforehand so that you have different sized fragments.

Pour the ‘blood’ through the sieve, highlighting that the holes in the sieve represent the tiny gaps in the capillary wall. I like to pour it from a great height so that it sprays everywhere (showing that the blood is under high pressure) and covers the cells below. Highlight that none of the red blood cells have passed through the holes and nor have most of the plasma proteins (the students should see some of the smaller bits of rice floating about in the tissue fluid but most will remain trapped in the sieve).

 

Atomic Structure

By the end of Key Stage 3 pupils are expected to be able to describe the structure of an atom, relate atomic structure to information given for each element in the Periodic Table and show the arrangement of electrons in shells around the nucleus. It is vitally important that pupils develop a secure knowledge of these fundamental concepts in chemistry since a superficial understanding can result in misconceptions and pose significant difficulties in understanding higher-order content such as ionic and covalent bonding at GCSE and beyond.

Take your time, break down the topic into bitesize chunks and use plenty of diagnostics such as hingepoint questioning to gauge the level of understanding of the whole class before moving forward together. In addition to the following activities, provide pupils with plenty of practice in relating atomic number and mass number to the number of protons, neutrons and electrons in a neutral atom, and drawing electron shells.

Hula hoop competition

Explain that all atoms consist of electrons orbiting a tiny nucleus then have a hula hoop competition! Who can keep their electrons orbiting for the longest?

Plasticine atoms

Provide pupils with laminated electron shells, an element symbol, a particle key and coloured plasticine. Ask them to build an atom of the element they have been given before taking a photograph and sharing it with the class via Padlet.

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Models

Build giant models of atoms using foam balls, craft straws, pipe cleaners and wire etc. These make excellent mobiles which can be hung in order of atomic number along the length of the science corridor.

Atomic cookies

Alternatively, bake (or buy) cookies and decorate them with proton and neutron M&Ms and silver ball electrons.

Facebook profiles or cubes

Facebook profiles or these simple cubes can be used to present information on all manner of things in science (e.g. famous scientists, types of nuclear radiation, specialised cells). Ask the pupils to investigate the element for which they built their plasticine atom and then complete a Facebook profile or cube for it. Who discovered it? When was it discovered? Is it a metal, non-metal or semi-metal? What are its properties?

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Lego Telomeres

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Telomeres are located at the ends of chromosomes. They consist of multiple repeat sequences and their main function is to ensure that when DNA is replicated, the ends of the molecule are included in the replication and not left out. When teaching the significance of telomeres, I use Lego to build giant chromosomes as this allows me to demonstrate the loss of a short section of each telomere during cell division (by removing Lego bricks) and the role of telomerase in replenishing it (by adding Lego bricks).