1. AGENDA – Looking Backwards, Looking Forwards CER Rough Draft
APRIL 06, OBJECTIVE – Students will be using proxy data to determine the plants growing in the Anacostia watershed at a specific time period in history and then using that information to determine the climate of the area. WARM-UP – Based on the 5 trees we focused on, which tree(s) pollen were most abundant ~12,500 ybp? In what climate do these trees thrive? Which tree pollen was most abundant ~340 ybp? In what climate does this tree thrive? Which tree pollen emerged only during 1 time period? In which climate does this tree thrive? HOMEWORK – Looking Backwards, Looking Forwards Quiz – 4/09
AGENDA – Looking Backwards, Looking Forwards CER Rough Draft

2. Citing Evidence Cite at least 3 pieces of evidence to support your claim. Write in complete sentences using proper spelling, grammar and punctuation. How did the data change from year to year? Make sure you specifically identify 3 different taxa (plant), % pollen sampled (not number of trees) and the corresponding years before present (ybp)
Sample
Out of the pollen collected, Sedges were declining. Sedges represented 23% of the pollen sampled ~ 12,500 ybp and declines to 1% of the pollen sampled ~ 340 ybp. Ragweed gradually increased over time. Ragweed represented 0% of the pollen sampled ~12,500-3,000 ybp but emerged to 14% ~340 ybp. Viburnium pollen was not present ~12,500-10,000 ybp but increased to 13% ~3,000 ybp and the percentage of pollen sampled decreased to 11% ~340 ybp.

3. Reasoning Focus Questions Scientific reasoning explains why/how the evidence supports the claim. 1. Why do scientists use fossilized pollen to make inferences about how the climate in the Anacostia Watershed changed over 12,500 years? Reference the Pollen article in your basket. 2. How do scientists determine the age of sediment cores? Reference the Sediment article in your basket Why was there a decrease in the % of pollen samples for birch, fir, oak and spruce from ~12,500 ybp to ~340 ybp? 4. Why was there an increase in the % of oak pollen samples found from ~12,500 ybp to ~340 ybp?