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Solar System Inner Planets for Kids

Kids will be fascinated and engaged in our Inner Planets activities to help kids learn about the solar systems 4 inner planets. The science unit covers Mercury, Venus, Earth, and Mars with lots of hands on science experiments and free worksheets for kids.

Inner Planets Hands on Science Unit for Kids K-6th Grade! Lots of fun ideas for kids learning about the 4 inner planets - mercury, venus, mars, and earth. Includes free solar system worksheets for elementary age kids #solarsystem #innerplanets #scienceunit

Hands on Solar System Unit

  1. The Sun
  2. The Moon & Astronauts
  3. Inner Planets (Mercury, Venus, Earth, Mars)
  4. Outer Planets (Jupiter, Saturn, Uranus, Neptune)
  5. Pluto, Asteroid Belt, Comets, and Stars

Inner Planets

We are continuing on in our solar system unit. We’ve talked about the sun and now we are ready to start learning about the Solar System’s Inner Planets for Kids: Mercury, Venus, Earth, and Mars. This is a really fun, hands on unit to help kids learn while having fun.


Mercury is a small planet and the planet closest to the sun. Only one space craft (Mariner 10) has gotten close to Mercury. During the day it is more than 750 F, but at night it gets down to -300 F.
Mercury Science Project for Solar System Unit for Kids
We made a model of mercury by mixing 1 cup of flour, 1/4 cup salt, 1 teas oil, and 1/4 cup water. After we’d shaped it we hit the planet with rocks of different sizes to make the craters Mercury is known for.


Venus is the hottest planet in the whole solar system because of it’s location nearby the sun and dense atmosphere the traps in the sun’s heat. There are volcanoes that spew lava on its surface.

Venus Science Project for Solar System Unit for Kids

Venus Science Experiment

To help the kids understand that Venus was so hot that rocks melted we set up this simple science experiment. We made a mound by overturning a custard dish and covering it and the surrounding area with flour. I showed them a 1/4 stick of butter was solid like rocks. I melted it in the microwave just like the heat melts rocks on Venus. Then we poured it over the center of the overturned custard dish so the kids would see it form streams. When it cooled down the butter turned back hard, just like the rocks on Venus.


We read several books  on earth discussing how the earth is the perfect home, the layers of the earth, how the atmosphere protects us (keeping us warm and burning up meteors before they hit the earth), how our tilt gives us seasons, and more.
Earth Science Project for Solar System Unit for Kids

Earth Science Experiment

For hands on activities consider making a playdough earth (showing the layers) or make a compass (because of our powerful magnetic field a compass always points north)


We learned the reason this planet is called the red planet is because the red look comes from the iron in the dirt. We talked about how scientists are hoping to have a colony on Mars someday (you can read more about this 2025 Mars settlement here)
This terrestrial planet has mountains, valleys, and volcanoes including a volcano called Olympus Mons the largest volcano in our whole solar system.
Mars Science Project for Solar System Unit for Kids

Homemade Volcano

To make our Olympus Mons we put red construction paper on a baking sheet. We put an empty 2L bottle in the center.
We wadded up paper around the 2L bottle to make the volcano. Then we covered the entire surface with our favorite playdough recipe tinted brown. The volcano looked amazing!
Now for the eruption! We put 6 teas baking soda in the bottle. In a separate measuring cup put 2 cups vinegar, red food coloring, and a squirt of dish detergent. When you are ready for the eruption pour the vinegar mixture into the bottle and stand back – it is going to erupt!
free planets worksheets for a solar system uni

 4 Inner Planets

Plus for every planet we studied the kids took notes on things they learned that were interesting using these free solar system worksheets for kids.

solar-system-unit-about-the-sun-for-kids Moon Unit for Kids Hands-on activity to learn about constellations using pipe cleaners, beads, and constellation flashcards for an engaging STEM activity! Use to teach preschool, pre k, kindergarten, first grade, 2nd grade, 3rd grade, 4th grade and more about stars, solar system, astronomy or as a fun, educational science activity

Solar System Activities

Looking for more fun, hands on science activities to teach kids about astronomy or to round out your solar system for kids unit. You will love these hands on solar system activities and lessons:

Kids will have fun learning about our solar system with these free printable Solar System Worksheets for kids.  You’ll find solar system vocabulary, planets, sun, stars, moon phases, and so much more! These free worksheets are great for Kindergarteners, grade 1, grade 2, grade 3, grade 4, grade 5, and grade 6 students. Kids will have loads of fun learning about different star formations and their names with this easy-to-make Constellations Cootie Catcher. This is the perfect addition to your solar system for kids unit with preschool, pre k, kindergarten, first grade, 2nd grade, 3rd grade, 4th grade, 5th grade, and 6th grade students FREE Moon Phases Mini Book

Free Solar System Printables

Plus, don’t forget to add these free solar system worksheets and printables to your lesson plan:

About the author

Beth Gorden

Beth Gorden is the creative multi-tasking creator of 123 Homeschool 4 Me. As a busy homeschooling mother of six, she strives to create hands-on learning activities and worksheets that kids will love to make learning FUN! She has created over 1 million pages of printables to help teach kids ABCs, science, English grammar, history, math, and so much more! Beth is also the creator of 2 additional sites with even more educational activities and FREE printables - www.kindergartenworksheetsandgames.com and www.preschoolplayandlearn.com

1 Comment

  • Loved the activities/experiments we just completed for the inner planets with our 2nd grader and pre-schooler!

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