Lab prep: You need to assign students to bring in soil samples from home and a straight sided water tight jar at least a week before. You will need a box of water softener, rulers, masking tape, markers, lab direction sheets, lab data sheets, newspapers.

This slide shows all of the materials that they will need This slide shows all of the materials that they will need. I stress to the students that they need to be ready to roll when they come thru the door to class. Take their soil outside to the sidewalk and on the news paper start sorting.

They will need to take out all of the leaf litter, rocks over ¼ in They will need to take out all of the leaf litter, rocks over ¼ in. and smash any clods. They need to have the teacher check it before they put the soil back in their jars. They will fill their jars just over ½ full with the sorted soil.

This is what the cleaned soil should look like This is what the cleaned soil should look like. They can pick up the newspaper from the sides ( taco style) to aide in getting it into the jars. I have them save the left over soil for another lab field method of soil texture determination.

After soil is in the jar this is to much After soil is in the jar this is to much. You can’t get enough water in the jar.

When they get back in side they need to add a heaping teaspoon of water softener to their jar before they add the water. I have the softener in several containers at the front of the room along with tape and markers.

They need to put a strip of masking tape on the jar before adding the water while the jar is still dry. Name, class period and date. They need to leave plenty of room for marking and labeling the different layers as they settle out.

They need to add water to within 1 in of the top of the jar and secure the lid. Students should note the time on their data sheet when they start to shake. They will then shake for a minute and then recheck the water. They may need to add more. They need to continue shaking vigorously for 4 more minutes. Up down, side to side and keep it moving the entire time. They need to then set it down and measure and mark the sand layer on the tape after 30 seconds has passed. I usually have them catch up on their notes for the lab at this time. Be sure the start time is recorded, their hypothesis is recorded. They can clean up some of their mess. They can move about the room and check out the other students jars. Remind them that they can’t move the jars around. Prep them on where the jars are going to go at the end of the period. Move around the room and assist students with the measurements as some will have a difficult time seeing through the murk. Note: if the sand is hard to see have them take the lid off and gently set the ruler down until it stops on the sand. This depth can then be transferred to the tape on the outside of the jar.

30 sec mark on the jar for sand.

Before the end of the period they need to make a mark for the silt Before the end of the period they need to make a mark for the silt. This will usually change when they look at it the next day. The silt will consolidate more and be a more defined layer. I usually have them go with the silt layer from day 2. Direct students to transfer their jars to the designated area with out tilting the jars. You will need to baby sit them until then as other classes come thru the room. Remind the students what is expected as they come in tomorrow. See next slide

As the students come into the room have them take the jars carefully to their tables with out tilting them! They will need to check the silt measurement again and establish a line for the clay. Some will need assistance with this. Students need to record all data on the data sheet and begin their calculations to determine the % of each layers. Have them check their work with you and then they can plot on the soil triangle.

Example of how to set up. The calculation

(48mm sand / 78mm total height) x 100 = 61.5% Sand (25mm silt / 78mm total height) x 100 = 32% Silt (5mm clay/ 78mm total height) x 100 = 6.5 % Clay Total = 100 % This shows how to do the calculations. If their numbers don’t come out to exactly 100% they may need to round one or two of the values up or down a 1/10 th of a %.

Remind them on the screen where the base lines are for each of the soil particles are as you click thru this slide. This could be the end on day 2 as they finish plotting their data onto the soil triangle and turn it in their data sheets This could be a stopping point before continuing with lab reports in the future. Question: How do your results compare with your hypothesis? If not why do you think they are different? What would you do different if you were to repeat this experiment. example: could you shake then set 24 hrs. and do one set of measurements? How would you test you theory? You should get similar results either way. This would fit into what's next on the lab report