Undergraduates achieve learning gains in plant genetics through peer teaching of secondary students

Abstract

This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non-majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS) students through a case study curriculum to discover the cause of a green tomato variant. The curriculum explored plant reproduction and genetic principles, highlighting variation in heirloom tomato fruits to reinforce the concept of the genetic basis of phenotypic variation. HS students were taught additional activities related to mole-cular biology techniques not included in the MS curriculum. We measured undergraduates' learning outcomes using pre/postteaching content assessments and the course final exam. Undergraduates showed significant gains in understanding of topics related to the curriculum they taught, compared with other course content, on both types of assessments. Undergraduates who taught HS students scored higher on questions specific to the HS curriculum compared with undergraduates who taught MS students, despite identical lecture content, on both types of assessments. These results indicate the positive effect of service-learning peer-teaching experiences on undergraduates' content knowledge, even for non-science major students.

Figure 1.

Comparison of mean (± SE) scores of MS undergraduates (n = 19) vs. HS undergraduates (n = 38) from pre- and posttests of SLP content knowledge from 2012. (A) Pretest. (B) Posttest. Asterisks (*) indicate significant difference between groups as determined by a Mann-Whitney U-test followed by false-discovery rate control. Hash marks (#) indicate significant difference between pre- and posttest score within the group, as determined by an exact Wilcoxon signed-rank test followed by false-discovery rate control. W, Z, and p values for all comparisons are reported in Table S2.

Figure 2.

(A) Comparison of mean (± SE) pre- and posttest scores for all undergraduates (n = 52) from 2013. Asterisks (*) indicate significant difference between pre- and posttest scores for each question as determined by an exact Wilcoxon signed-rank test followed by false-discovery rate control. (B) Comparison of mean scores (± SE) from posttests of MS undergraduates (n = 24) and HS undergraduates (n = 28). Asterisks (*) indicate significant difference between groups as determined by a Mann-Whitney U-test followed by false-discovery rate control. W, Z, and p values for all comparisons are reported in Table S2.

Figure 3.

Comparison of mean (± SE) scores of MS undergraduates (n = 24) vs. HS undergraduates (n = 28) from pre- and posttests of SLP content knowledge from 2013. (A) Pretest. (B) Posttest. Asterisks (*) indicate significant difference between MS undergraduates and HS undergraduates as determined by a Mann-Whitney U-test followed by false-discovery rate control. Hash marks (#) indicate significant difference between pre- and posttest scores, within the group, as determined by an exact Wilcoxon signed-rank test followed by false-discovery rate control. W, Z, and p values for all comparisons are reported in Table S2.

Figure 4.

Comparison of final exam scores from 2012. (A) Percentage of correct answers to individual questions pertaining to material taught by undergraduate students. Questions 1–4, genetics questions common to both MS and HS curriculum; questions 5–6, questions specific to HS curriculum. Asterisks (*) indicate significant difference between MS undergraduates and HS undergraduates as determined by a Mann-Whitney U-test followed by false-discovery rate control. (B) Mean scores (± SE) represented as percentages of the four common curriculum questions, the two HS-specific questions, and the other exam questions. Asterisks (*) indicate significant difference between MS and HS for that question set, as determined by a Mann-Whitney U-test followed by false-discovery rate control. Hash marks (#) indicate significant difference from other exam questions, within the group, as determined by an exact Wilcoxon signed-rank test followed by false-discovery rate control. (C) Mean scores (± SE) represented as percentages of the 70 lecture-only questions and the four lab and lecture questions. MS, n = 23; HS, n = 37. W, Z, and p values for all comparisons are reported in Table S2.