I am a big fan of Google Classroom and although I am not completely paperless quite yet, I am increasingly using Google Docs in class and when setting assignments for homework.
I think one of my greatest discoveries when completing the Google Certified Educator courses (available here and highly recommended) was the fact that you can embed YouTube videos directly into a Google Form then share it with your students as a flipped learning activity. There are a variety of different question types available including text and multiple choice as well as more advanced options such as scales for ordering or sequencing.
The students’ responses are automatically collated in a Google Sheet document allowing you to add comments, apply conditional formatting or review their learning before the lesson.
My students love sushi and there are a proliferation of conveyor belt restaurants in Bangkok. Not only do they serve delicious food but they also make an excellent model of the human circulatory system. Let me explain.
I usually start the lesson by showing the students five minutes of this video ‘Japanology – conveyor belt sushi’. I ask the students if they have ever been to this type of restaurant before and what they like about it. We discuss some of the advantages and disadvantages of conveyor belt restaurants.
I then ask the students to imagine that they are running a conveyor belt sushi restaurant in Bangkok. The restaurant is really busy and there are lots of hungry customers waiting to be fed. They need to get the food to the customers more quickly. How do they do it? Allow a few minutes for the students to Think, Pair, Share. (e.g. tell the chefs to get a move on and increase the speed of the belt motor).
I then tell the students that empty plates are piling up but there are no waiters to collect them. How could they solve this problem without employing more waiting staff? (e.g. the customers should put their empty plates back onto the belt so that they are returned to the kitchen).
At this point I tell the students that conveyor belt sushi restaurants are similar to the human circulatory system (this tends to be met with lots of ‘ohhs’ and ‘ahhhhs’ as they realise that I haven’t completely lost the plot by talking about sushi in Biology).
The students are asked to extend the analogy by comparing the parts of the restaurant with parts of the circulatory system using a comparison table or bridge maps (bridge maps are used to visualise analogies by quite literally bridging the gap between the familiar and the new. The line of the bridge shows the common relationship that exists between two or more pairs of things).
The students should consider what each of the following represents in the human body and most importantly why (the relating factor):
The sushi (e.g. oxygen or nutrients);
The empty plates (e.g. deoxygenated blood);
The conveyor belt (e.g. blood vessels);
The chefs who prepare the food and put it on the plates (e.g. the lungs);
The motor which makes the belt go round (e.g. the heart);
The hungry customers (e.g. body cells).
Refer back to your opening questions about how best to get sushi to the hungry customers quickly and what to do with the empty plates. How does this relate to the circulatory system?
The activity should be extended by asking the students to evaluate the model. Are there any ways in which the comparison doesn’t quite work? Can the students think of any other ways of modelling the circulatory system?
This is a good lesson to have just before lunchtime because everyone gets very hungry!
There are lots of fun experiments and demonstrations for showing the movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient (diffusion). Here are some of the methods I use.
One demo that is often used is dropping purple potassium permanganate crystals into a basin or beaker of water and observing the slow dissolution and diffusion over time.
Cup of tea
Provide students with a tea bag (fruit tea bags are best because the colour change is more vivid) and a beaker of hot water (or water of different temperatures). Look at the factors affecting the rate of diffusion by telling the students that you are thirsty and want to speed up the time it takes to make your morning cuppa – how can they do this? (e.g. heat the water, put more tea into the tea-bags or teapot, reduce the volume of water).
Prepare agar plates and then ask the students to carefully cut a 1 cm wide moat around the circumference of the agar using a scalpel. Fill the moat with food colouring. The circle of agar represents a cell and the food colouring, the extracellular fluid. Over the course of the lesson the food colouring will slowly diffuse through the agar into the ‘cell’.
If you position a camera phone above the agar plate using a clamp stand and film using the time-lapse function you can capture and speed up the whole process to then show the students in summary at the close of the session. See video below:
The classroom will smell like a changing room but a very simple method of demonstrating diffusion is to spray deodorant in one corner and then ask students to raise their hands when they smell it. This creates a ‘Mexican-wave’ effect as the particles diffuse through the air.
The most effective way of demonstrating diffusion through a semi-permeable membrane is to fill dialysis tubing with starch and place it in iodine solution. The iodine will diffuse through the dialysis tubing (turning the starch blue-black) but the starch particles (being too big) will not diffuse in the opposite direction.
If anyone has any other fun demos of diffusion I would love to hear them!
DNA is a complex macromolecule and so it is no surprise that students often find it difficult to get their heads around the double-helix.
The structure of a polynucleotide can be effectively modeled using sweets and string or cocktail sticks. Marshmallows actually work best for the sugar phosphate backbone but here I’ve used fruit chews instead. I also used four different coloured jelly beans to represent the bases which make up the ‘rungs of the ladder.’ The sweets won’t last long so keep them until the next lesson on DNA replication and then illustrate the action of helicase by asking the students to cut them down the middle (through the ‘hydrogen bond’ cocktail sticks) and throw them away.
The sweet model illustrates the polynucleotide structure really well but it is a bit fragile to twist into a double-helix.
Instead, use this excellent resource on mygenome.org to build your own origami DNA. There is a step-by-step instructional video which the students accessed from their iPads, allowing them to pause and rewind as and when they needed to.
Sadly, it’s only available to UK schools. Here in Thailand, Year 7 students have been learning about the conditions necessary for germination and we now have lots of different seedlings growing in planters in the corridor outside my classroom.
I often find that really simple visual aids are all that are needed to make otherwise quite complex concepts spring to life in the students’ minds. For example, a balloon inside a cardboard box to represent the protoplast inside the cell wall of a plant cell (particularly useful when teaching plasmolysis), pipe cleaners as polysaccharide chains or for demonstrating protein structure, and drawing pins stuck in ping-pong balls as viruses or cell-surface antigens.
Cubes are great for displaying information or for modelling structures like the human skin or the cross-section of a leaf. They can be hung in the classroom so also make eye-catching displays. Templates are easy to find online.