This experimental research aims to find out whether reading activities have any effects on science-concept achievement The reading activities are defind as (a) passage summarizing (b) new relevant examples giving (c) significant points identifying and (d) passage synthesizing. Five groups of Mathayom Suksa two students at Phuncharoen Withayakhom School, sixteen students each, are randomly selected. These five groups have similar Thai language ability background. Each subject is instructed to read 3 different passages, followed by one of the reading activity, except one is control group. All subjects are tested their science-concept learning achievement. To make the experiment more valid, each student is given two additional measure; animal interest inventory and reading ability test. The data are collected and analyzed using ANACOVA with 2 covariates. The results are as follows: There are significantly different among the five groups (p< .01). A pair comparison results show that the only control group (p< .05). These findings indicate that reading activities have some effects on the learning science-concept achievement, particularly the passage synthesizing.