What a cool thing to be doing with your home schooled kids.
Use some plastic foil from used packaging (clear fruit punnets or toiletry gift boxes) to make a piramid with no base or top. See enclosed photo. You need 4 shapes that you will stick together with transparent tape. Each shape had a 6 cm base, 5 cm height and 1 cm top.
When sticked together search a hologram video on your phone or tablet, place the projector on the screen and play. As simple as that. Adults and kids will like it just as much. Have fun.