Embed a Timer into Google Slides or PowerPoint

Google Slides

Go to Google Drive, Click New, Select Google Slides, create your presentation.

On the appropriate slide, Click Insert, select video

From menu, search YouTube for a countdown video of appropriate length (ex: 45 second timer)

Select the video you want it will be embedded into your slide.  Position it on the slide as needed.

When you “Present” the presentation, the video will appear and you click it to start and pause.  (Hint: there are countless timer videos with sound and other features)

PowerPoint

Open PowerPoint and create a presentation

On the appropriate slide, click the Insert Tab, select Video, select Online Video

Search YouTube for a timer of your choosing (ex: 45 second timer)

Select the video you want, click insert and it will be embedded on your slide.  Make sure to position and resize it as needed.