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Engaging Science Students in the Design & Enactment of Assessment
Introduction

The general design was that there were three sources of scores: from the teachers, the peers, and self. The teacher (and the teaching assistant) rated students’ performances in a learning activity according to the pre-agreed criteria. Self- and peer-assessments were conducted by students rating themselves and their classmates’ performance either individually or in groups, also using the set of pre-agreed criteria. The approach used in self-assessment, however, was not solely based on the performance scores students gave themselves, but was based on how accurately they could assess themselves.

Performance indicator can be obtained by assigning appropriate weights to the following components
     (a) teacher score (T);
     (b) peer score (P);
     (c) the difference of self and teacher scores (S-T);
     (d) the difference of self and peer scores (S-P).

The following table illustrated how RAW scores for the component in (b) and (d) could be computed when there were five assessment criteria (C1 to C5) and four groups (G1 to G4). Suggested methods to compute the FINAL scores for the component (b) were presented in the next table.

Table: Computing the RAW Scores for the Components P and S-P – An Example
Criterion Peer-assessment Self-assessment Peer average score   Comparison of Self- and peer-scores  
G1 G2 G3 G4
C1 x11 x12 x13 x14 pc1=(x11+x12+x13)/3 |x14-pc1|
  2 3 4 1 (2+3+4)/3=3 |1-3|=2
C2 x21 x22 x23 x24 pc2=(x21+x22+x23)/3 |x24-pc2|
  6 7 8 5 (6+7+8)/3=7 |5-7|=2
C3 x31 x32 x33 x34 pc3=(x31+x32+x33)/3 |x34-pc3|
  2 3 4 3 (2+3+4)/3=3 |3-3|=0
C4 x41 x42 x43 x44 pc4=(x41+x42+x43)/3 |x44-pc4|
  7 8 9 8 (7+8+9)/3=8 |8-8|=0
C5 x51 x52 x53 x54 pc5=(x51+x52+x53)/3 |x54-pc5|
  8 9 10 10 (8+9+10)/3=9 |10-9|=1
Average         Raw peer-score
= (pc1+pc2+pc3+pc4+pc5)/5

=
=(x11+x12+x13+x21+x22+x23+x31+ x32+x33+x41+x42+x43+x51+x52+x53)/15		 Raw S-P score for G4 is obtained by taking the average of the absolute differences in the above cells
 

Raw peer-score
= (3+7+3+8+9)/5=6
=(2+3+4+6+7+8+2+3+4+7+8+9+8+9+10)/15
=6

Raw S-P score
=(2+2+0+0+1)/5
=1

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Table: Methods to Obtain FINAL Scores from RAW Peer Scores – An Example
    Method 0 Method 1 Method 2 Method 3
Group Raw peer-score

Theoretical range=(0,10)		 Final score=raw score

Theoretical Range=(0,10) 		Teacher assigned score, based on ranks, maximum
= 20 marks,
each rank
= 3 marks		 Multiplied raw score by the constant 3

Theoretical range=(0,30)		 Transformed proportionally

Desired range=(3,15)
G1 10 10 Rank 1:   20 marks 30 15
G2 8 8 Rank 2:   17 marks 24 9
G3 7 7 Rank 3:   14 marks 21 6
G4 6 6 Rank 4:   11marks 18 3

The methods proposed in this table could be used in a similar manner to obtain FINAL scores for the S-P component. However, the higher the RAW S-P scores, the lower the FINAL S-P scores.

The methods suggested in the above two tables could be used to produce FINAL scores for the components T and S-T.

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