No whiteboard, no problem!
There is good evidence that effective dual coding (designing your explanations so that the same information is presented both verbally/in text and visually without too much extraneous/distracting info) is a useful technique to help students visualise invisible concepts/processes, see links within/between topics, simplify complex material, and recall the information more easily, therefore promoting learning.
For a complete guide for teachers from Oliver Caviglioli see here: https://teacherofsci.com/dual-coding-theory/
For a great blog on some of the pitfalls to avoid see: https://www.learningscientists.org/blog/2016/11/17-1
Within Biology there are a large number of concepts that lend themselves to visual representation. I don't think I have ever taught a lesson where I have not drawn a diagram at some point: be it diagrams of the molecules, cells, organ systems or concepts and processes that are less easily seen such as chemical reactions, ecosystems and nutrient cycles.
Drawing diagrams live as you explain and develop the ideas, rather than having a static and complete diagram on the board, has major advantages in terms of reducing split attention effect, reducing cognitive load, allowing you to chunk the information and practice the parts separately and allowing students to see how to construct the diagrams for themselves. For a lovely series of blogs on using visuals to enhance explanations see Pritesh Raichura's blogs here: https://bunsenblue.wordpress.com/2019/12/04/clear-teacher-explanations-2a-dual-coding-processes/
I had come across the following quote from Adam Boxer, along with his review of why he uses visualisers, but didn't really think much of it as I have always drawn diagrams on the Whiteboard/Smartboard during lessons and didn't think I could justify the cost when it seemed to be working fine.
"Using visualisers generally has without a doubt made me a better teacher, and if you have staff who really want to focus on their modelling and exposition then they need a visualiser in their classroom."
I was concerned when lockdown started that I was going to struggle - I don't have any touch-screen devices at home so I had thought my only option was trying to draw in the Smartboard software using the mouse pad on my laptop - I tried this, with much failure, in the first few weeks. I then came across a post on Twitter showing a DIY visualiser set-up - using their phone with a home-made Lego stand. I decided to give it a go.
I realised my music stand could make a good visualiser stand and tried connecting my phone as an extra camera in Zoom. Sadly there is no support for Android devices. Thinking cap back on. Finally, with the help of the good people of Youtube, I solved the issue by
Downloading Zoom on my phone,
Joining my own Zoom meeting from my mobile
At the point I wanted to draw, sharing my phone's screen and opening the camera.
My first attempt (thankfully with my 6Bs who are less easily derailed by these things) was a steep learning curve. Things to bear in mind include:
Switch off notifications from other apps (the students do not need to read my WhatsApp messages from my mum about her cat!)
Make sure your sound is off on the second device or the feedback is terrible
Make sure the focus mode is changed to infinite touch focus (or the camera will shift the focus on the pen/your hand rather than on the page)
Make sure your phone has enough battery - I always have mine plugged in if I'm using it now...
Even given the 'Heath Robinson' nature of my set up I can see a number of advantages that I had not really considered before and am thinking that I would quite like a visualiser when I get back into the classroom.
Things I have found useful
Far neater and easier than trying to construct on the computer / Whiteboard
Far easier for the students to draw along with you and produce their own versions of the diagrams to help them remember key information and focus on the important details.
Can be removed/covered and then put back quickly to allow for recall practice and checking answers.
Don't have to rub off when you run out of space - the diagrams are all still there if students have questions later - can screenshot them and add them to the Smartboard notes for the lesson if you want to.
Facing students (not such an issue in lockdown - but in the classroom would mean they can hear me better (without me having to stop and turn round), I can monitor visual clues to their understanding and they are more likely to stay on task if they know I can see them.
I can practice beforehand and have practice versions in front of me that are exactly the same size, colours, layout etc. as the one I am going to draw in the lesson - reducing my CL so I can concentrate on the explanation, not on scaling up / dealing with thicker pens / running out of space
A visualiser would also allow me to quickly share good examples of student work and demonstrate aspects of practicals without the issue of moving all the kids round my desk and back to their seats