Disappearing Tracks

Bob the Builder™ just poured fresh cement next to the sandbox. When the vehicles drive through the sandbox their tracks are clear, however when they drive through the fresh cement the tracks seem to disappear! Mix up your little builder's own cement and compare the tracks to those in the Mash & Mould Playsand.

Difficulty: Easy
Build Time: 5 minutes
Must be 3+
Supervision of children using materials such as glue, scissors, etc. is strongly recommended.
Download Blueprint

Supplies needed:

  • Measuring cup
  • Water
  • Cornstarch
  • Bob the Builder vehicles (Mash & Mould and/or die-cast)
  • Mash & Mould Playsand
  • Shallow container
  • Wooden spoon

The Blueprints

1. Measure one cup of cornstarch into the shallow container. Then add 1/2 cup of water to the container.

2. Mix the water and cornstarch together slowly with a wooden spoon. The incorporated mixture will have properties of both a solid and a liquid. If you and your little builder slowly push a finger in the substance it will sink to the bottom like a liquid. Squeeze it tightly and it will act like a solid.

3. Flatten the Mash & Mold Playsand on a flat surface.

Drive your little builder's Bob the Builder vehicles through the sand to create tracks.

4. Drive your vehicles through the cement mixture. Push down hard as you move them across the container. Watch the tracks disappear!