
When Charlie takes a tumble off her bike and scrapes her knee, her sister Alex reassures Charlie that she'll be okay. Alex tells Charlie all the ways her skin works hard to heal itself. Charlie learns how blood begins to clot right away to stop bleeding, how the body removes...

When Charlie takes a tumble off her bike and scrapes her knee, her sister Alex reassures Charlie that she'll be okay. Alex tells Charlie all the ways her skin works hard to heal itself. Charlie learns how blood begins to clot right away to stop bleeding, how the body removes...