# For Kids: Mathematics and Our Bodies

[Originally published as Math Moment: Math & the Human Body]

VIDEO TRANSCRIPT: Our bodies are remarkable. We can eat, see, move, smell, and so much more. Weâ€™re clearly incredibly designed! But when we use math to see how our bodies work, we get a deeper appreciation for how amazingly God knit us together.

Notice that a childâ€™s head is bigger in comparison to the rest of its body than the adultâ€™s head. A big head helps protect a child when they fall. However, if we kept growing with that same ratio between our head and body, we wouldnâ€™t be able to walk as adults! God gave us just the body proportions we needed for each stage of life.

While weâ€™re talking about our heads, letâ€™s zoom in on our ears. It takes advanced math, including trigonometry, to record sounds digitally so that we can listen to them. But our bodies constantly collect and interpret sounds for usâ€¦all without us thinking about it!

Now, take a look at these cells from a human body. Notice that the cells are approximately spheres. Using math, we can explore the cell’s surface area and volume of cells as they grow.

Here are the formulas for the surface area and volume of a sphere.

The ratio between them would be the division of one over the other, which we can show using a fraction line and which simplifies to 3/r, whereÂ r stands for the radius of the sphere. The radius, orÂ r, is going to get bigger as the cell gets bigger.

What happens to the surface area? Letâ€™s say this cell has a radius of 1 and this one of 3.

Notice that if we plug those values into 3/r, the ratio gets smaller as the radius gets bigger. That means that in comparison to the volume, thereâ€™s less surface area. This would be problematic if our cells kept growing, as the cell absorbs nutrients through its surface area. If the cell gets too big, it will die, as it wonâ€™t be able to get enough nutrients. But donâ€™t worry â€” our great Creator designed cells to divide into smaller cells before they get too big. Once again, math helps us see his design.

Next, letâ€™s talk about the viscosity of our blood. I know “viscosity” is a big word, but it basically describes the thickness of a liquid. Water has a lower viscosity than the orange liquid shown here.

Hereâ€™s the formula for viscosity. God put special proteins in your blood that make these values just right for your blood to flow around your body and to change when you get a cut so the blood becomes thicker and you donâ€™t bleed to death.

God sure thought of everything, didnâ€™t he?

Now, thereâ€™s a lot more we could say about our bodies, but hopefully, that gives you a glimpse into how incredibly designed you are. God knit you together in your motherâ€™s womb. He knew all that would take place in your life before you took your first breath. You can trust him and cast your cares on him because he cares for you.

## Written by Kate [Loop] Hannon

After having her own view of math transformed, Katherine has been researching, writing, and speaking on a biblical worldview of math for more than a decade. She's the author of the popular Principles math curriculum series published by Master Books. Her books on math and a biblical worldview have been used by individuals, homeschool groups, and Christian schools and colleges. Receive a free video on transforming math at www.christianperspective.net/math/transforming-math