If you're putting together a talk or an interactive workshop you might use slides or worksheets to accompany what you're talking about. Even for online workshops, slides can be screenshared or included in a video feed, and worksheets can be converted into interactive Desmos pages or shared as PDFs with schools ahead of time, to print for the class.

Slides are a great tool, but there are a lot of clichés about how they can be misused. Here's a set of tips for Powerpoint without the 'ow' (or, if you're a Mac user, Keynote without the 'no').

• Slides should complement what you’re saying, but not replace you -“If your slides make sense without you, what's the point of you being there?”.
• You shouldn’t be reading long passages of text from slides – use them to accent particular terms (if people see a term written down, they can more easily Google it later!) and show images/diagrams, but not for long form text; some recommend no more than six words on a slide. Having a written version of what you’re saying is useful for some people for accessibility, and can be useful as a handout if it’s specifically requested, but if you put up a pile of text, the room will stop listening to you and read it themselves – maybe missing the points you’re trying to emphasise.
• Text on slides should be big and readable – stick to a minimum font size. If you can make the text bigger, make it bigger! White text on black is easiest to read (with the bonus that black slides don’t have visible edges on a projector screen, so you can’t tell as easily if it’s misaligned). You don't need text on every slide: it's a valid approach to only put something on a slide as text if it's something you'd like the audience to be able to spell so they can search for it later, or if they'll need to be able to remember it during the session to understand what you're saying.
• Slides are great for making things visual – so make use of this! If you want to show a number is big, write out the whole thing so it looks impressive.
• If you’re including images in slides, make them as big as possible (>1000px across is a good benchmark) – and if they’re grainy, find or take a higher-quality version. Graphs and diagrams can be useful, but only if they’re there for a reason: to illustrate a point, or summarise what you’ve been talking about. Use alpha in Keynote, or Photoshop, to get rid of ugly background rectangles. Some plots or graphs may be hard to see on a projector: make sure the lines are thick enough, which may involve remaking a plot yourself rather than using an existing one, or zooming in on the relevant part.
• Make sure you have permission for all the images and video you’re using. Use (good!) photos you’ve taken yourself, learn about CC licensing, find copyright-free images/video from websites like Pixabay, Pexels or Dupe, and give image credits on slides where necessary.
• Set up your slides so they only include the ones you’re using. There’s nothing worse than seeing someone click through interesting-looking extra slides just because they couldn’t be bothered to spend 2 minutes before the session hiding the ones they don’t need - and you can use on-screen tools to skip to specific slides if you run short on time.

Handouts and worksheets are a great way to make an in-person workshop interactive, give people something tangible to take away, and make use of the way school students have been trained to engage with photocopied materials.

• Worksheets shouldn’t have too much text to read, especially if you want people to be listening to you when you hand them out. Show a picture of the worksheet on a slide, and only give them out when you’re ready for people to start working on the activity. This goes for electronic/interactive worksheets too.
• Test out your worksheets - if you find yourself wishing you had more space to write, or some extra space for notes or diagrams, your students will too. Show them to other people for feedback as well.

For both slides and worksheets, think about accessibility – high-contrast text and diagrams are easier to see for everyone, and colour palettes should be colour-blind-friendly (examples can be found online). Make sure you have large print versions of your worksheets ready in case they’re needed (not just printing your existing worksheets on bigger paper, or hastily enlarging the font so all the page elements move!)