Valentine’s Day Science Activities

Feb 10, 2024 | Articles, Math Activities, STEM

Valentine’s Day Science Activities

Did you know that you can make slime light up a bulb? How does the heart pump blood throughout your body? How far can you launch a Q-tip? Answer these questions, and come up with more of your own with these open-ended science activities.

By Nicole Rhodes, Lead STEM Tutor

The following three science activities are great for open-ended questions while exploring topics in STEAM (science technology engineering art math). The first is a model heart valve that can be modified to maximize pumping efficiency. The second, a miniature Cupid’s bow and arrow allows for practice estimating and measuring distance as well as modifying a design. Finally, a heart-shaped circuit design with…slime! 

Heart Pump Model

How does your heart pump blood with each beat? To model a heart valve, you can build a simple pump with a balloon, drinking glass, and straws in this science activity. Kids can really get into the pumping–and even race to see who can pump the most “blood” the fastest!


  • balloon
  • scissors
  • 2 cups
  • 2 straws


  1. Fill a glass halfway with water and red food coloring to mimic blood. 
  2. Cut the stem off a balloon to fit over a glass or mug. Stretch the balloon over the glass.
  3. Poke two small holes into the balloon, about ½ inch apart from one another, and a little to the side of the center. 
  4. Poke two straws into each hole. If the balloon is not completely sealed around the straws, you can add tape. 
  5. Press on the balloon to pump the “blood” through the straws and into another glass. 

Ask your child what they notice about the pump. How is the pump moving blood up the straw? How does our heart pump blood throughout our bodies, even against gravity? How could you change the pump model to be more like a real heart?

Cupid’s Bow & Arrow Contest

Engineer a miniature bow and arrow that shoots the farthest, fastest, or most accurate. This activity is best to do outside–make sure you aim your arrows away from anyone! Or, you could take it a step further, and make heart-shaped targets at varying distances for some more Valentine-themed fun.


  • popsicle sticks
  • Q-tips
  • dental floss
  • large nail clippers
  • bowl of warm water
  • markers to decorate (optional)
  • measuring tape


  1. Soak the popsicle sticks for about an hour or more in warm water. You might want to soak more popsicle sticks than you think you will need because some are bound to break in the process. 
  2. Gently and slowly bend the popsicle sticks into a bow shape. It might be helpful to use a rounded surface such as the side of a mug to help form the bow. 
  3. Have an adult use large nail clippers to make notches on each side of the popsicle sticks. 
  4. Tie dental floss as the bowstring. Pull it taut to maintain the slight bend in the popsicle stick.
  5. Clip one end off of a Q-tip to make an arrow, and decorate your bow and arrows with markers if you like. If you are having a contest with multiple participants, it is helpful for each contestant to have uniquely colored arrows. 
  6. Go outside, and aim your arrow away from people and animals. You can make a heart-shaped target, and tape it to the side of a tree. To use your bow, hold the blunt end of the Q-tip on the middle of the bowstring, and pull back, using the edge of the popsicle stick bow as a guide. 

How far did your arrow travel? Make an estimate, then use measuring tape to measure the true distance. How can you improve your accuracy and/or distance? You might want to sand or cut a small nick into the middle of your bow to guide your arrow. Does this improve distance or accuracy?

Slime Circuits 

How does electricity travel through conductive materials? I love this circuit activity because it does not rely solely on wires. Instead, it uses the conductivity of water through the matrix of slime. You can also mold the slime into an endless variety of shapes to explore the efficiency of electronic current. Research conductivity and make modifications that can strengthen your circuit.


  • LED bulb 
  • 9-volt battery
  • Wires
  • Masking tape or electrician’s tape
  • Slime Ingredients
    • ½ cup clear glue, approximately one entire 4 oz glue container (optional: use glow-in-the-dark glue!) 
    • 2-3 tablespoons Sodium borate (aka Borax–available in the cleaning supplies section of many markets)
    • ½ teaspoon baking soda
    • red food coloring (optional)
    • heart-shaped cookie cutter (optional)
    • ¼ cup water
    • bowl

 Part 1:  Make Conductive Slime

  1. Dissolve 1/2 teaspoon baking soda in ¼ cup water. 
  2. Optional to modify conductivity with either  ½ teaspoon of salt or sugar.
  3. Mix in 1/2 cup of clear glue (or glow-in-the-dark glue, for extra luminescence!)
  4. Slowly add in sodium borate (aka Borax). Mix the slime very slowly to reduce the number of air bubbles that get stuck in it. Gradually add the sodium borate while mixing and kneading thoroughly until the slime comes together and can be kneaded by hand.

Part 2: Build Your Circuit 

  1. Tape wires to the anode (+) and cathode (-) of the 9-volt battery. Be sure that the wires do not touch, as this will short your circuit. Check your LED by touching the the anode (longer end) of the bulb to the anode wire, and the cathode (shorter end) of your LED to the cathode (-) wire. The LED should illuminate.  
  2. Now insert the ends of each wire into two different pieces of slime. 
  3. Connect the two slime pieces with a LED bulb. Be sure that the anode (longer end) of the LED is inserted in the same piece of slime that the battery anode (+) is attached to. 
  4. Insert the cathode (-) end of the LED into the same piece of slime that the cathode wire is connected to. 

Notice where you placed your bulb and wires. Try moving them around to different locations. Does this change the brightness of the LED? What makes the LED not light up? 

The water in slime is naturally conductive, but adding salt or sugar can add to conductivity–you can experiment with different additions to see which makes the bulb light up the brightest! If you add glow-in-the-dark glue, there is a different luminescent action happening. The glowing comes from phosphors, which are activated when energy from light or the sun is added.


Want more Valentine’s Day and February STEM? Check out:

And if you love STEM, make sure to check out our summer camps here.


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