I call students to the gathering area. We review the difference between weathering and erosion. Weathering is the breaking down of materials, but erosion is the movement of those broken-down pieces. I tell them that today we are going to look at some different forms of weathering and erosion.
I tell students that today they will be using their senses to observe weathering and erosion. We will need to wear goggles to protect our eyes. I always tell students that they cannot use their sense of taste during this exploration.
I assign students to groups of four and send them to their workspace. On their workspaces I have four cheap chocolate cookies (the cheaper the better for this exploration as they fall apart better!) Students record their observations for each exploration on their observation sheets.
I give each group, three soak-resistant paper plates, three chocolate chip cookies, four Q-tips, four toothpicks, a small cup of water, and a timer.
Students place the first cookie on the first plate. They try to break the cookie up with the Q-tip. Not much will happen so I only let them try this method for about a minute. Students record their observations on their recording sheet.
Students place the second cookie on the second plate. They use their toothpicks to erode the cookie. I ensure that students wear goggles for this activity as pieces of cookie start to fly around. The toothpicks don’t make much of a dent in the cookie, but things do begin to fly off when toothpicks are used. Students record their observations on their recording sheet.
On the third plate, students place the third cookie. Someone in the group is the timer. Students pour water onto the plate and time it for a minute. They lift the cookie gently to see if anything has changed. Students record their observations on their recording sheet. Students continue to time the cookie in the water for five minutes and record their observations again.
Students record their conclusions about which form of erosion was most efficient.
I call students to the gathering area and tell them to stay in their exploration groups. I give each a 6 by 6 by 6 cube of legos. Each cub must be the same size, but could have different size pieces making it up. I tell them that this is their group’s rock.
I tell students that they will demonstrate erosion in a relay race. Students must break off one piece of lego, place it on his/her chest and crab walk it across the room to a specified location without dropping it. Students quickly realize that some groups have fewer pieces and may be making more progress than others that have small lego blocks in their rock.
Once the game is played I call students back to the gathering area and we discuss how the water eroded the cookie. Students observed that water broke down the cookie much faster and more efficiently than the Q-tip or toothpick. We discuss that water is a powerful force in the erosion process. Wind is more like the Q-tip, and human activity is like the toothpick.
Once students have completed discussing the cookie erosion exploration, I turn their attention back to the lego rock relay. Students may become heated again as they begin to discuss how fair or unfair the race was. We talk about the fact that not all erosion happens in a uniform manner. Softer rocks may break into bigger pieces while harder rocks may take longer or break off in smaller amounts during the erosion process. Students realize that this was the point of the erosion relay. They understand that not all erosion happens in the same way or at the same rate.
At the end of the lesson, I give each student a chocolate chip cookie. I told students at the beginning of the lesson that they could not taste the materials, so it is fun to give them a cookie at the end. I am careful to ensure they are nut free in case of allergies.