Cheap, temporary blackout curtains for grandparents' house?

[mommyshoppinghabit]

My kids are staying over my parents' house in a few weeks. When they don't have something to block outside light in their rooms, it takes them a long time to fall asleep and they wake up very early. The rooms that the kids will be staying in have venetian blinds up, but no curtain rods. I don't want to make my parents have to nail anything like a curtain rod into the window trim, so trying to think if I buy some black fabric and velcro it up, will it hold and will it come off? Is there a way I can hang the curtain using the venetian blinds?

[lifeguard]

You could tape or tack a heavy blanket over the window.

[rainyday]

We've taped up newspaper layers using painters' tape when we've been in a situation with no window coverings at all. Usually we just throw a couple of heavy blankets up over the blinds or whatever.

Is the top of the venetian blinds strong enough to support a couple of heavy blankets? What about putting in just three or so nails in the top of the window trim (so holes wouldn't be visible when the nails are pulled out) and then clipping quilts or heavy blankets up? Binder clips work well for this.

[SubliminalDarkness]

Black poster board. It works perfectly.

[bigteamug]

black posterboard, dark sheets or blankets.

What about buying a thrift store sheet to use when they go again? More durable in the end.

[cycle]

They make temporary shades that stick on, I think they are called Redi-shades, they make a light blocking one. They really block the light, like pitch dark when it is daytime! They come in only a couple of sizes and you can cut them to fit your window size.

[LeighPF]

Safety Pins

I would pin something thick over the windows and around the top bar of the blinds (the really thick part where all the cords are).
And make sure the cords are baby safe.