Students should return the sample they just tested, and get another sample. They are to repeat steps 3 - 5 until all the samples have been tested. After taking all the samples, students should finish filling out the data table. If a pH meter is not available, students can use litmus paper. For this, the teacher will need to tell the students what the different samples are.
Students can determine the percent of substances that are within the acceptable range.
The student displayed safe laboratory practices throughout the entire investigation. The student did not need to be reminded of the rules. The student displayed safe laboratory practices during most of the investigation. The student did not display safe laboratory practices throughout the investigation. The student constantly needed to be reminded of the safety rules.