Make a copy of the Sticker Collection Slide. It's a Google Slides document where you can paste the stickers that you earn.
Want to make your own sticker collection sheet in Google Slides?
Start a new Google Slides document.
Go to File → Page Setup. Change to Custom and change to Pixels. Enter 1920 x 1080 and click Apply.
Go to Slide → Edit Theme. Click one of the layouts. Delete the text. Design your background. Click the X in the top right corner.
Right-click (or two finger click) the slide preview in the Slide Sorter. Choose Apply layout and click your background.
Add a text box for students to enter a name.
Add this as an assignment in Google Classroom. Or, click the Share button change the setting so that Anyone with the link can view. Click Copy link and then click Done. Paste the think somewhere and change the /edit in the URL to copy. When students follow this link, they will be prompted to make a copy.