
Some animals take long naps. Hibernation is when animals sleep for a long time during winter. Groundhogs hibernate. They dig deep burrows under the ground. They stay safe and warm in their burrows.
Photo Credit: Brian E Kushner/Shutterstock
On July 1, we say thank you to people who … read more
About 20,000 years ago, ice covered much of Earth. Temperatures … read more
Animals use camouflage to survive. Camouflage is a way that … read more
© 2026 McGraw-Hill Education. All Rights Reserved.