Canva is a free online graphic design tool which can be used to make beautiful posters, infographics, presentations and many other things. It is extremely simple to use and features a vast library of templates, fonts and photographs to choose from.

My AS level biology students have recently used Canva to create eyecatching infographics summarising the structure and properties of biological molecules. I think they look great!

Allopatric Speciation in the Lower Congo River

Central Africa’s Lower Congo River is home to an extraordinary assortment of fish—many truly bizarre. This  video by Science Bulletins, the American Museum of Natural History’s current-science channel, features Museum scientists on a quest to understand why so many species have evolved there. It provides an excellent case study of allopatric speciation and helps to dispel the myth that populations only ever become isolated on islands. A Google Form worksheet to accompany the video is available here.

Google Forms for Flipped Learning

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.

Teaching Diffusion

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.

Potassium permanganate

Potassium 1potassium2potassium3potassium 4

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).

Agar ‘cells’

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’.

agar1agar 3

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.

Dialysis tubing


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 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.

And here is the finished result!


Not Quite Rocket Science

I’ve just been reading about a brilliant project being run between the UK Space Agency and the RHS in which participating schools can grow seeds that have been sent into space.

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.