Children are naturally inquisitive, with a keen interest in learning. As preschoolers and toddlers, they are remarkably curious creatures with an insatiable appetite for both knowledge and an understanding of how and why things work.

Here are five easy science projects that will nurture that yearning for learning, projects that toddlers will enjoy and comprehend.

THE SUN-BLOCK EXPERIMENT

Although words like “photosynthesis” and ”global warming” are probably a bit much for your average toddler, you can instill some of the basic learning blocks of the sun’s energy and how we rely on it with this simple project, courtesy of First-School.

Take a paint-can lid, or an empty paint can itself, and place it on top of a patch of green grass in your yard. Use a heavy object to keep the lid in place.

Explain to the child that the sun provides the grass (and plants and flowers) with food and nutrients needed to keep growing, and that in a few days, the patch of grass under the lid will start to lose its color because it is hungry and in need of the sun’s rays.

Wait a few days and remove the lid to show your child the discolored patch of grass. Replace the lid in the exact spot and wait a few more days to show the child how much lighter the grass has now become.

Take away the lid or can and have the child monitor how quickly the circular spot returns to a lush green.

MAKE YOUR OWN TOOTHPASTE

A warning: It won’t taste nearly as good as the Buzz Lightyear toothpaste currently spread on the brush each morning, but it isn’t that bad, and kids will probably get a kick out of the do-it-yourself aspect.

According to Preschool Education, give the child a spoon and a plastic bag to start. Put bowls of baking soda, salt, and water on a table, and explain to the child that by carefully measuring certain ingredients, they can make anything from food to, well, toothpaste.

Using measuring spoons, put four teaspoons of baking soda, one teaspoon of salt, and one teaspoon of water in each plastic bag. Add in a drop or two of food flavoring extract, such as peppermint or orange, and have the children mix the ingredients by gently squeezing the closed bag.

Voilà! Personal toothpaste for the next morning.

GROW YOUR NAME

Again from the folks at preschooleducation.com comes this fun experiment.

Take a small box, line it with plastic or Saran Wrap, and have children fill it with potting soil — enough to cover the plastic, but not too deep.

Have the grandchildren use their fingers to scratch out their names in the potting soil. Then sprinkle grass seeds where they etched their names. Cover with more potting soil, a few drops of water, and put the box on a windowsill near sunlight. In a few weeks you should see the children’s names growing in grass in their own special garden.

THE HIDDEN RAINBOW

Easy and colorful, this project from HobbyScience shows a grandchild how a rainbow of color is hidden in simple black and white. Any child who has a trough full of crayons will immediately be intrigued as to how you’re going to make a rainbow out of the two blandest, simplest colors.

Using a black felt-tip marker, place a dot in the center of a white coffee filter. Put a small amount of water on a plastic plate or a saucer. Set the filter on the plate for a few seconds and remove.

Hang the filter to dry. Try to engage the preschoolers in a modicum of patience, and watch what happens. The black spot on the coffee filter dipped in water suddenly begins to spread in a virtual tie-dyed display of colors.