Rethinking Teacher Evaluation in Chicago

Presents findings from the Excellence in Teaching Pilot, which included training and support, classroom observations, and feedback in principal-teacher conferences. Examines implementation issues and the validity and reliability of observation ratings

Ray Brown to Walter Lyons

https://egrove.olemiss.edu/lyons/1034/thumbnail.jp

Influence of Soil Water Potential and Environment on the Internal Water Status of Grasses

The water relations of two grass species, smooth brome (Bromus inermis Leyss.) and intermediate wheatgrass (Agropyron intermedium (Host) Beauv.), were studied under a range of environmental conditions in a growth chamber. The environmental conditions included three temperature regimes (day/night temperatures of 15/10, 20/15, and 25/20 degrees centigrade), and three vapor pressure deficits within each temperature regime (6.2, 8.8, and 11.4 millimeters of mercury). Short wave radiation was maintained at 0.5 calories per square centimeter per minute with a 14 hour photoperiod, and wind speed was constant at 45 centimeters per second. Six plants of each species were studied simultaneously under each of the nine environments, and each set of conditions was replicated once. The plants were subjected to a single severe wilting cycle, usually requiring about 4 days. Just prior to when the lights came on and the temperature increased each morning, the soil water potential, leaf water potential, and leaf osmotic potential (of frozen-and-thawed tissue samples) were measured for each plant using Peltier thermocouple psychrometers. At this time of the day the water relations of the plant are the most favorable, and measurements taken then will reflect a base-line condition under which the plant can potentially recover from daytime extremes. Leaf pressure potential was calculated as the difference between leaf water and osmotic potentials. One hour after the lights came on and the temperature increased, leaf resistance was measured with a diffusion porometer, and leaf temperature was measured with a Barnes infrared radiometer. Leaf water potential, osmotic potential, and soil water potential all decreased progressively each day under continued water potential all decreased progressively each day under continued water stress in both species, while leaf resistance and leaf temperatures increased. Generally, leaf and soil water potentials decreased more rapidly and to a lower extreme under the warmer environments than under the cooler ones. Soil water potentials remained about 10 bars higher than leaf water potentials throughout the entire wilting cycle, as measured one hour before the lights came on, with no significant differences between species. Leaf resistance increased as leaf water potential decreased, becoming asymptotically higher as the leaf tissues became drier, with no significant differences between species. A critical leaf water potential was not identified at which leaf resistance increased sharply, perhaps because these factors were determined only once daily. Leaf temperatures also increased as leaf water potential decreased in both species. The differences between leaf and air temperatures were greater at low leaf water potentials under the cooler temperatures were greater at low leaf water potentials under the cooler temperatures. For both species under all conditions, the difference between leaf and air temperatures increased steeply at the higher leaf water potentials, but tended to increase less steeply at the higher leaf water potentials, but tended to increase less steeply at low leaf water potentials. The relationship between leaf pressure potential and leaf water potential is believed to be of considerable importance. As the plant progressively dries out, this relationship shows that the pressure potential declined from an initial high of about 10 bars, eventually reaching zero, and then becoming negative. With continued drought, the pressure potential became progressively more negative, ultimately reaching a minimum, and then increased toward zero bar again. This J shaped relationship appears to describe the wilting process in plants. The leaf water potential at which pressure potential first reaches zero was termed the physiological wilting point , and appears to provide a quantitative measure of incipient wilting. It is proposed that when the minimum pressure potential is reached, individual cells begin to collapse as air penetrates between the cell wall and the plasma lemma. The leaf water potential at which this occurs was termed the point of protoplast collapse , and is believed to represent permanent cell damage. It is believed that when the pressure potential reaches zero the second time, a condition of tissue death exists wherein virtually all of the cells have collapsed. The results of this study provide important information concerning the wilting phenomena in plants, and illustrate the possible mechanisms by which it occurs. The use of these techniques and relationships provide quantitative criteria by which the water relations of different plant species can be evaluated. Also, they suggest some potentially important ecological implications regarding the adaptability of plants to arid environments

Factors affecting productivity of highway construction operations

The Tennessee Department of Transportation (TDOT) presently schedules highway construction projects using past experience along with some production rates obtained from historical data. Just recently TDOT has changed the way contracts are awarded. In the past TDOT awarded contracts with a working day deadline. This style of contract lead to some unreasonably long project durations. In order to alleviate this problem, TDOT has decided to change contract deadlines to a calendar date, a type of contract which requires the contractor to complete the contract on or before a given date. With the new style of contract being used, TDOT has to be extremely confident in their scheduling techniques to avoid any unnecessary claims that may result if the scheduled time is too short. To aid in the development of improved scheduling techniques, TDOT funded a research project at the University of Tennessee to investigate 22 highway construction operationsThese tasks were chosen because they make up approximately 75 percent of the time duration on typical highway construction projects. This thesis concentrates on the factors affecting productivity of highway construction operations and presents a methodology for predicting productivity of cyclic operations which accounts for the various factors affecting productivity. Field data were collected for both cyclic and non-cyclic highway construction operations. The cyclic operations were tested using statistical analysis procedures in order to determine the most appropriate statistical model to use when predicting future production rates. The most appropriate model for use with highway construction cycle times was determined to be the lognormal distribution. After determining the most appropriate distribution, a predicted productivity rate (P95) was calculated with a 95 percent confidence level. It was found that there were several factors that affected the productivity of highway construction operations. Many of the operations were affected by more than one factor during an observationThe most often encountered factors were: delays, site conditions, resources, start-up and finishing-up operations, bunching effect, regional factors, and the amount of working days to calendar days. All of these factors are broken down further and examples are given in order to better explain how these factors affect the productivity of highway construction operations

Growth Seed Yields, and Seedling Production of Native Prairie Plants In Various Habitats of The Mixed Prairie

The native vegetation of the mixed prairie of west-central Kansas was subjected to the worst drought on record during the period 1933 to 1939 inclusive. Data secured from the United States Weather Bureau reveal the fact that precipitation during this period of drought was far below normal . The rainfall deficit as reported by Albertson and Weaver (1942) was nearly 35 inches for this 7-year period. Other climatic factors such as wind movement, relative humidity, and temperature were equally abnormal. The extreme drought period greatly modified the vegetation of the mixed prairie and the short-grass disclimax. The basal cover in these t-wo types of vegetation before the drought ranged between 65 and 95 per cent. During the 7 years of deficient rainfall, however, this cover was reduced to nearly zero in many places and an average cover of 1 to 20 per cent was common (Weaver and Albertson, 1940). The direct causes of loss in vegetation were deficient soil moisture, overgrazing and dust carried by wind from cultivated fields and deposited upon the prairie vegetation. The reduction of plant cover resulted in large denuded areas that became extremely susceptible to wind erosion. As range depletion became more extensive the need for a sound conservation program in relation to soil erosion, range management and revegetation became evident. The present research is concerned with determining the yield of seed in pounds per acre , and the number of seedlings produced in relation to basal cover, habitat and climatic conditions

A Study of the Units of Credit in Social Science Offered by Entrants to South Dakota State College of Agriculture and Mechanic Arts in the School Years 1951-\u2752 and 1952-\u2753

The purpose of this problem is to determine from the transcripts of graduates of accredited South Dakota high schools the number of units of credit in Social Science that were offered for admission to South Dakota State College of Agriculture and Mechanic Arts in the school years of 1951-\u2752 and 1952-\u2753. (South Dakota State College of Agriculture and Mechanic Arts shall hereinafter be referred to as State College.) Specifically stated, the aims of this study were as follows:1. To determine the mean total amount of Social Science offered by entrants from South Dakota high schools when they were admitted to State College in the school years 1951-\u2752 and 1952-\u2753.2. To determine to what degree the entrants to State College have met the minimum legal requirements in Social Science for high-school graduation. 3. To show to what degree these entrants\u27 offerings in Social Science have varied for the graduates from large, medium and small high schools. 4. To show the difference in amounts in the offerings in Social Science wade by men and women entrants. 5. To show the number of units, in the different fields of Social Science, offered by the average student entering State College. The population of the study are samples of entrants to State College in the years 1951-\u2752 and 1952-\u2753 who are graduates from accredited high schools from the state of South Dakota