Describe diagrams and illustrations
Sciences rely heavily on diagrams (molecular structures in chemistry, circuit schematics in physics, cell diagrams in biology, etc.). For every such figure, provide descriptive alt text capturing the essential information.
- For example, a chemistry diagram of a molecule should at least list the atoms and their connections (“Ball-and-stick model of water: an oxygen atom bonded to two hydrogens, forming a bent shape”). If the instructional point is about geometry or bonding, mention that in the description. In biology, an image of a cell should have alt text like “Diagram of an animal cell with labeled organelles (nucleus, mitochondria, etc.)” and you can elaborate in accompanying text about each organelle’s role if that’s part of the lesson.
- Complex processes (like metabolic pathways or physics free-body diagrams with multiple forces) may need a longer description outside the alt text – possibly a stepwise explanation of the process or a list of components. Benetech’s Diagram Center guidelines and resources on complex image description can help craft effective descriptions.
Top
Accessible chemical notation
Chemistry presents unique challenges since equations (reaction formulas) and the periodic table are visually dense.
- To make chemical formulas accessible, write them in linear text when possible (e.g., “H2O” or “2 H₂ + O₂ → 2 H₂O” can be understood by screen readers if you use standard notation and include subscripts where appropriate).
- In cases of complex formulas or organic structures, include a description (“Glucose molecule, represented as a ring of 6 carbon atoms with OH and H side groups…”).
- Consider providing an accessible periodic table – for instance, the American Chemical Society offers an HTML periodic table that a screen reader can navigate cell by cell, reading out element symbols, numbers and atomic weight. Linking to or providing such a resource is more accessible than a static image of the periodic table.
Top
Caption science videos and add audio description
When demonstrating experiments or scientific phenomena on video, ensure captions are available for any speech and consider the visual information being conveyed.
- Often, science videos have critical visual-only content (color changes in a reaction, movement of an apparatus, etc.). Try to narrate those actions or results verbally in the recording itself so that a listener knows what is happening.
- In a chemistry demo, you might say, “Now I will pour the polyvinyl alcohol solution into the borax solution… it turns into a gel-like solid” – describing the action and outcome. This integrated description is ideal, but if that’s not in the original video, you can add an audio description track or write a supplementary description of what happens in each step.
- Tools like Panopto allow adding a secondary audio track or notes; at minimum, provide a written step-by-step summary of demonstrated experiments for those who can’t see them.
Top
Laboratory data and charts
Whether it’s a physics lab graph of motion, a chemistry titration curve, or a biology chart of population growth, ensure data is accessible. Include data tables for graphs (so a student using a screen reader can navigate the numeric values) or at least summarize the trend/conclusion in text (“As time increases, the voltage drops exponentially to half within 5 seconds”).
- If using color graphs, label lines directly (e.g., “red line: trial 1, blue line: trial 2”) or use distinct patterns so that those with color vision deficiencies or using black-and-white printouts can differentiate.
- Modern tools like Excel allow you to add alt text to charts and to ensure chart elements (axes titles, legends) are tagged for screen readers. As a quick check, try navigating your chart with a screen reader or export it through Ally to see if the auto-generated alternative is intelligible – Ally can often produce a descriptive HTML version of common chart types, which you can refine.
Top
Simulations and interactive content
Many science courses use digital simulations (e.g. PhET interactive simulations for physics and chemistry, virtual labs for biology). When choosing these, look for those that have accessibility modes – for instance, PhET sims now have an accessibility filter (some include screen-reader support and alternative input).
- If a simulation is not fully accessible, provide an alternative path: e.g., offer a video demonstration or a series of screenshots with descriptions so that students who can’t use the interactive can still follow the concept.
- Provide keyboard instructions if an interactive requires input (like “press arrow keys to increase temperature”) and ensure those are documented for students who can’t use a mouse.
Top
Terminology and notation clarity
Particularly in biology and chemistry, complex terminology can be a barrier for some students (especially those with dyslexia or other cognitive processing differences). Provide glossaries or define acronyms and symbols on first use.
- Instead of assuming everyone knows “ATP”, write “ATP (adenosine triphosphate, the cell’s energy molecule)” at first mention. This not only helps all learners understand but also assists text-to-speech users who may benefit from seeing the expanded form. Similarly, format chemical notation clearly in text (H2O using subscript tags or the equation editor so it reads as “H two O”).
- If you have students with print disabilities, offering an audio version of complex nomenclature (Ally’s audio format or Microsoft Read Aloud can speak chemical names, though sometimes mispronounced) can supplement visual text.
Please also see our guides on:
NOTE: This content was adapted from the UMBC Office of Accessibility and Disability Services.
Top