LEARNING GOAL: Use data to build a conceptual understanding that the presence and/or absence of light is important for controlling circadian and circannual rhythms.  OBJECTIVE: Construct an explanation of how light affects circadian rhythms by analyzing the nature of circadian and circannual rhythms within organisms

True or false: The maximum height the Sun reaches in the sky on any given day is the same everywhere on Earth Recall that: Summer Solstice (first day of summer): June 21, 2015 Fall Equinox (first day of fall) September: 23, 2015 Winter Solstice (first day of winter): December 21, 2015 Spring Equinox (first day of spring): March 20, 2015 FALSE

Draw this on your paper List natural events that signal a change in seasons Summer   Fall Winter Spring Write a claim that identifies which of the factors listed on your paper would cause birds to migrate or bears to hibernate (or other behavioral responses you listed). A claim is a statement explaining a phenomenon and is based on evidence. Example answer: Day length is important because it signals to birds to migrate. (CLAIM) Seeing geese migrate south in September and migrate north in the spring supports my claim, since days start to get shorter after the summer solstice and longer after the winter solstice. (JUSTIFICATION/EVIDENCE)

Explain your claim and the justification What observations or inferences can you use to support your claim? An inference is an explanation of a concept or phenomenon based on evidence. Evidence can include observations you have made. What can you use to support your justification? How does your claim demonstrate an organism’s ability to adapt to its environment? How do organisms respond to changes in seasons? How do organisms benefit from changes in seasons?

DISCUSS How many claims identified a nonliving factor as the most important factor? How many identified a living factor as the most important? How do nonliving factors impact living things? In what ways are humans affected by seasonal change?

Circannual rhythms Circannual rhythms (e.g., migration, hibernation, etc). A seasonal change such as day length, or the amount of daylight an area receives. How does the amount of daylight an area receives affect plants and animals?  

Circannual rhythms Yearlong Cycles These geese form a "V" shape when migrating.

Circadian rhythms Daily Cycles Morning Glory flowers close at night and open again in the morning.

IN SUMMARY Environmental triggers may vary, but you are going to focus on one that you know exists: day length. The amount of day length is critical for plants and animals. Day length refers to the length of time there is light in the sky on a daily basis. We will continue the investigation during our next Circadian Cycle!