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Home » Early Years Science » How to make the perfect sandcastle

How to make the perfect sandcastle

Modified: May 24, 2021 · Published: Jul 17, 2019 by Emma Vanstone · This post may contain affiliate links · 7 Comments

Now summer seems to finally be here, we thought we’d get the sand table out and start playing. We tried to make sandcastles with the dry sand, which didn’t work at all. They just collapsed.

Can you think why this is? What could you add to make the sand more ‘sticky’?

Summer science challenge - make the perfect sandcastle

We added a little bit of water, which made the sandcastles slightly better, but still not great.

Collapsed sandcastle - summer science for kids

We kept adding water until we could make an almost perfect sandcastle. It took several attempts to get the right combination of sand and water.

Too much water and the sandcastles fell apart and stuck to the inside of our bucket. Too little water and the sand just flowed out. We found that if we could squeeze the sand into a ball in our hands and it stayed together it made a good sandcastle.

How to make the perfect sandcastle

Sandcastle sand to water ratio

According to PBS the magic sand to water ratio is one bucket of water to 8 buckets of sand!

We put this theory to the test and it worked really well! The sand was sticky, but not too sticky…almost perfect!

Why does water make sand stick together?

You should have noticed that wet sand is much stickier than dry sand. This is because the water forms tiny bridges between the grains of sand which holds them together. This is due to the surface tension of the water. If too much water is added, water fills the space between the grains of sand and the bridges break down.

Read more about the physics of sand on Live Science.

More Science Activities using Sand

Use sand to filter water in this easy activity.

Make a volcano eruption using sand.

Or, try one of our 50 Summer Science Activities.

Image of sandcastles on the beach for a making sandcastles science activity
The BEST sandcastle sand to water ratio

Last Updated on May 24, 2021 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

Comments

  1. Jodi

    June 03, 2012 at 5:02 am

    Love how you incorporated learning into playing. That’s the best.

    Reply
    • ScienceSparks

      June 03, 2012 at 9:13 pm

      Thank you. x

      Reply
  2. maryanne @ mama smiles

    June 04, 2012 at 6:40 pm

    I love this – never thought about why you needed wet sand to get it to stick before!

    Reply
  3. Jane, Enchanted Wood Toys

    June 06, 2012 at 8:15 pm

    Children are never too young to learn things like this, especially when it is wrapped up in so much fun. However much or little they take on board at the time, doing something like this helps lay the foundation for a love of learning. More please!

    Reply
  4. Beth

    June 08, 2012 at 10:52 am

    I love how you incorporate Science into so many things I would never think of! You always have such fun ideas for makeing Science Fun =-) Thanks for linking up to TGIF! Have a great weekend,
    Beth =-)

    Reply
  5. Carrie

    June 08, 2012 at 6:29 pm

    Oh, how interesting. I love reading your science bits so I learn something. Thank you for sharing at Sharing Saturday!!

    Reply

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