"Where Did the Water Go?" Science Lab

Hello blog readers! It has been awhile! A lot has happened since I last posted in February. I have an excuse for not posting in so long, and here he is! Our precious baby boy will be 6 weeks old tomorrow.

I have received so many comments requesting the "Where did the water go?" lesson from this post, that I decided to go ahead and publish it. I have to give credit to my fabulous coworker, Jennifer Crumpton, who shared this lesson with me. We do this lesson every year on the first day of school, and it does a fantastic job of getting students excited about science. I thought it would be nice to post it now because you have to get together some materials that most of us probably don't have on hand.

Where Did the Water Go? 

This lesson is more of a demonstration than an actual science lab that students participate in. You will put 3 small paper cups in front of the students. You will pour water into one of the cups and then mix the cups up (like they do at sporting events where you have to guess which cup has the ball under it). The students will guess which cup has the water in it. You will "test" the cup by turning it over on a student's head. Your kiddos will be amazed when no water comes out of any of the cups!

Ahead of time you need to order some sodium polyacrylate (the stuff they put in disposable diapers to absorb liquid). You can order it here. You will want to practice this demo once or twice before you do it in front of your students.

Get three small paper cups (make sure you can't see through them). Before the students arrive, put a heaping teaspoon of the sodium polyacrylate into one of the cups.

 from teachersource.com 

What You Do:
1) At the beginning of the lesson, use a graduated cylinder to pour 50ml of water into the cup that you already put the sodium polyacrylate in. (If you don't have a graduated cylinder, you can just pour the water until a gel forms in the bottom of the cup. Using the graduated cylinder is a good way to show students how important it is to be exact when measuring during science labs).

2) Tell the students to keep their eye on the cup you poured the water in while you mix up the three cups. Keep moving the cups around until you think the students have gotten the cups confused.

3) Next, ask the students to guess which cup has the water in it.

4) Once they have chosen a cup, ask them how you can test whether the cup has water in it. Tell them you're going to test the cup by turning it over on a student's head! Randomly choose a student (you don't want your little friends thinking you have favorites!)

5) Walk up to a student and turn the cup over on their head. The kids will go crazy!

6) Do the same thing with the next two cups.

7) Once students realize that no water came out of any of the cups, have them write up a lab report. This is a great way to introduce the scientific method on the first day. Here's what I have them write in their science notebooks:

Question: Where did the water go?

Hypothesis: (They write what they think happened and why they think it happened). They can also share their hypotheses with their groups and with the class.

Observations: (They write down everything they saw me do.)

(Have students discuss what they think happened again. Then tell them your secret and write the conclusion together as a class.)

Conclusion: The water was absorbed by a polymer called sodium polyacrylate. The polyacrylate used in this activity is found in disposable diapers. 

If you have the funds, you can purchase enough sodium polyacrylate to send some home in a baggie for each of your students. Make sure they know not to try and sniff or taste it!! They will enjoy performing this trick for their families, and it will answer the question of "What did you do at school today?" If you try this lesson, let me know how it goes!

Here is a blog post from Educational Innovations that has a variation of this lesson as well as some other lesson ideas for using sodium polyacrylate. Have fun!



  1. First of all, congratulations on that sweet baby!!

    Secondly, thank you for sharing this cool activity!! I can't wait to share it with my 5th graders!! !:)

    Enjoy your weekend!
    Selena Bragg

  2. Thanks Selena! I'm glad you stopped by. I hope you enjoy your weekend too!

  3. Totally loved this science activity. I think it will be a great way to inspire and encourage critical thinking. You better bet that I pinned this!

    Congratulations also on your sweet sweet baby. What joy (and exhaustion!) you must be experiencing. :)

  4. That experiment sounds like so much fun! I am a third grade teacher moving to fifth grade and many of the experiments around our school are repeated throughout the grades...I love having something that they probably haven't experienced in my bag of tricks! Thanks for posting it!!

  5. Your baby is SO PRECIOUS! Congrats! I'm a new follower. I just nominated you for the Versatile Blogger Award. Check it out and enter to win my giveaway! http://www.nerdynerdynerdy.com/2012/07/blogger-awards-and-my-first-giveaway.html

  6. Congratulations! I've nominated your for a blog award. Please come visit teachingfifthgradeinpearls.blogspot to receive your award!

  7. Thanks Jen and Stephanie! If you try this lab with your kiddos let me know how it goes!

    Mrs. Thompson and Stacey,
    Thanks for nominating me! I am heading over to your blogs right now. :)

  8. I can't wait to try this lab with my kids! We are getting a new Science Curriculm this year and I would love any other fun science ideas you have!

  9. Thanks Dawn! Have you checked out thesciencelife.blogspot.com? She's a new blogger with awesome science ideas!

  10. Hello, once again,

    I am getting ready to order the sodium polyacrylate, and was wondering how much I should order? I'm hoping you have some insight for me regarding the quantities available for sale on-line...

    Thanks so much!

    You can respond here on your comments, or feel free to drop me an email at selenabragg@gmail.com... Whichever is most convenient for you is good with me!

    Selena Bragg

  11. Hi Selena! I think you'd be okay with the 4oz size if you only plan on doing it a couple of times. If you want to do it year after year, or if you want to give out tablespoons to each student in a baggie to take home, you may want to get the 1 lb size.

    Here's the website that sells it: http://www.teachersource.com/product/sodium-polyacrylate-diaper-polymer/chemistry

    I hope that helps!

  12. So sweet of you to respond... off to order it right now! Have a great week, and many blessings to you! (I will let you know how it works!) ;)

  13. Linda - Just ordered some - I think my students will love this! Nice intro to critical thinking and the scientific method with some humor thrown in. Perfect for the first week! If I can pull it together enough to take pictures for my blog, I'll send you the link.

    Mrs. Allen’s 5th Grade Files

  14. Corrina, I'm so glad you're going to try it! I can't wait to hear how it goes!


  15. I loved reading this piece! Well written!

    Merlen Hogg

  16. Gonna try this on my first day with fifth grade! Thanks for sharing!

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  20. I love this idea. I was just wondering what happened to the sodium-polyacrylate-diaper-polymer when you poured it over the student's head?