Twitter can be a great source of professional development, inspiration and collaboration for teachers. Just the other day I was looking for a hands-on activity with which to demonstrate elastic potential energy and energy transfer and so I tweeted for ideas. Here are some of the wonderful suggestions I received from the Twittersphere. Thank you everyone for your contributions!
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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.
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.
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 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.
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.
The half-life of a radioactive substance is the time it takes for the number of parent nuclei in a sample to halve, or for the count rate from the original substance to fall to half its initial level. Half-life is random and it is impossible to know which individual parent nucleus will be the next to decay. LEGO and M&Ms can be used to model this random decay while also negating the need for students to handle radioactive materials.
Students start with 100 M&Ms (other sweets can be used so long as there are two distinct sides e.g. Skittles) and tip them into a tray. Record the number of M&Ms which have landed face-up (these represent parent nuclei which have decayed). Remove these ‘decayed’ nuclei and tip the remaining M&Ms into a second tray. Once again count the ones that have ‘decayed’ and repeat until all of the M&Ms have gone. Use the data to plot a half-life curve.
Students throw 60 2×2 LEGO bricks into a tray and remove all of the bricks that land studs-up (these represent parent nuclei which have decayed). Stack these bricks together to show the activity i.e. the number of decays per throw. Throw the remaining LEGO bricks and again remove those that have ‘decayed.’ Stack these into a second column and place this next to the first to quite literally build an activity vs. throws bar chart. Repeat until all of the LEGO bricks have gone.
Electricity is something that students encounter every day of their lives. However, there tend to be lots of misconceptions and these are best addressed at Key Stage 3 and GCSE by using models and analogies to explain what are otherwise abstract concepts.
Below are four methods of modelling electric circuits but it is important to remember that not all of them need to be used at once and that their value lies not only in students identifying the ways in which they work well but also in evaluating their limitations.
Students sit in small groups (4-5 students) and hold a plastic hula hoop (or loop of rope) loosely in their hands. One of the students acts as the cell / power supply and begins to turn the hula hoop in one direction. The main message here is that the current moves at all points at all times in a circuit (a common misconception is that the current starts at the cell and slowly makes its way in procession through the wire).
The students will also feel some heat from the friction of the plastic hula hoop as it passes through their hands. This demonstrates that energy is being transferred but that the electrons themselves are not being used up (another common misconception). This model can also be used to introduce resistance i.e. for a given power supply, a higher resistance (i.e. a tighter grip on the hula hoop) will result in a lower current.
A student plays the part of the cell / power supply with a big plus sign on their right shoulder (positive terminal) and a big minus sign on their left (negative terminal). The remaining students are electrons and should arrange themselves in a tight circle (the circuit) around the edge of the classroom. Remind the students that electrons are negatively charged and, as such, repel each other (so they need to spread out evenly rather than clump together).
The student (electron) nearest the ‘positive terminal’ is pulled into the ‘cell’ and then pushed (gently!) out of the ‘negative terminal.’ As a result, this student will bump into / move close to the student standing next to the ‘negative terminal’ who, in turn, will be repelled and move away. This repulsion is repeated all the way around the classroom until a new ‘electron’ is pulled into the ‘cell’ at the ‘positive terminal.’ The whole process should be repeated and sped up to create a giant electric circuit.
Highlight that the push or shove from the ‘cell’ represents the voltage. The more powerful the cell, the bigger the voltage it gives to each electron. Finally, model resistance by placing two rows of chairs, through which the students have to squeeze, along one side of the classroom. As with the hula hoop model, the students should see that in a series circuit, if they are slowed down in just one small section of the circuit the current is reduced everywhere.
As above, the students should arrange themselves in a tight circle around the classroom. One student is the ‘bank’ (cell / power supply) and another is the ‘shop’ (bulb) which is located someway further down the road. At the bank, each student is given ten pounds (use Monopoly money) which they must then spend in full at the shop and therefore return to the bank with nothing (herein lies one limitation of the model as some energy is required for the current to get back to the battery).
Next, pretend there are two bulbs in series of equal brightness or, in other words, two neighbouring shops in which each student spends an equal amount of money (the ‘bank’ should give each student ten pounds in two £5 notes in order to model this). Extend the activity by asking the students to model what would happen if there were two bulbs of different brightness or how the model would differ in a parallel circuit.
Before building electric circuits, it can be useful for students to draw circuit diagrams on mini-whiteboards and then use sweets to demonstrate what is happening at each component. For example, if each sweet represents 1 V and the students are using a 6 V cell then they should start with just six sweets. If there are two bulbs in series but one is twice as bright as the other, how many sweets (volts) does each bulb require? Again, extend this activity by asking students to consider what would happen in different series and parallel circuits.
The cartesian diver is a classic experiment for illustrating buoyancy and the ideal gas law. However, students and teachers can find it fiddly to invert the test tube into the top of the bottle without losing all of the water. So instead, use a ketchup sachet (which contains a small pocket of air) – it works just as well!
A couple of nice activities using Oreo cookies (or in my case, cheaper alternatives).
Explain that the upper cookie is the lithosphere, the creamy filling is the asthenosphere, and the lower cookie is the lower mantle. Begin by simulating the motion of the rigid lithosphere plate over the softer asthenosphere by sliding the upper cookie over the cream. Then break the top cookie in half and simulate a divergent plate boundary by sliding the two cookie halves apart.
Push one cookie half under the other to make a convergent plate boundary.
Finally, simulate a transform plate boundary by sliding the two cookie halves past one another. Students should feel and hear that the two ‘plates’ do not glide smoothly past one another (thus modelling the earthquakes that occur at transform fault lines such as San Andreas).
Simply remove the top cookie to reveal the creamy filling beneath. Scrape away and shape the cream to show the phases of the moon. Students should draw the relative location of the Earth and label the phases. Great as a revision tool or plenary.
There is no need to fear the Van de Graaff generator (although advice from CLEAPSS should always be followed). However, a fun alternative to charging up students is to stack aluminium pie cases on top of the metal dome and watch them fly off in all directions as the electrostatic charge accumulates.
If It's Green Or Moves 