Measuring the Knowledge Increase of Eight Grade Students in a Bilingual

In recent years, the issue of using bilingual education has come to the public’s attention. A widespread belief is that students in bilingual classes achieve a higher competence in the language, but that they lag behind in subject-specific knowledge when compared to fellow students in traditional (i.e. monolingual) classroom settings. Nevertheless, by evaluating knowledge gain in a short teaching unit, previous studies have shown that bilingual students rarely experience drawbacks. Although there are a variety of different opinions, the present study aims at detecting how subject-specific knowledge is influenced by bilingual biology lessons. The study was conducted at a grammar school in North Rhine-Westphalia, Germany, with 13- and 14-year-old students. To assess differences in students’ knowledge gain, test and control groups were used, in which students were taught 12 identical biology lessons in a bilingual and a traditional classroom. The unit consisted of basic characteristics seen in (social) insects. Both classes took a knowledge test before and after the unit. We hypothesised that there would be a higher increase in knowledge for the bilingual class compared to the monolingual class. Results suggested a slightly higher knowledge gain in bilingual students, but no significant differences were revealed.


Introduction
The study at hand researches how bilingual classes influence subject-specific knowledge in biology.From a parent's perspective, the decision becomes difficult when faced with choosing to enrol their child in a bilingual or a mainstream class.Apart from additional language benefits (Bredenbröker, 2000;Dalton-Puffer, 2008;Lasagabaster, 2008), it seems reasonable that parents might fear that their child will lag behind in that particular subject, as he/she must not only keep up with the content but deal with it in another language.Furthermore, teachers are not entirely convinced about the effectiveness of bilingual education as well (Müller-Schneck, 2006), and it is considered particularly difficult to assess students in bilingual programmes, as it remains uncertain if mistakes are caused by the language barrier or by lack of knowledge.
The article will introduce the concept and organisation of bilingual education in Germany and give a short overview of current research about content learning.Not only will we explore the relevance of bilingual education from a student's perspective, but problems and fears that parents might have about bilingual education will also be addressed.Subsequently, a research question and hypotheses will be raised, which are followed by a description of the study's design.Finally, the study's results will be presented and discussed, ending with concluding remarks to encourage further research.

Bilingual education in Germany
Bilingual education has developed from a unique phenomenon to a mainstream movement (Appel, 2011, p. 85).The concept's promotion by politics, the Ministry of Education and several cultural affairs committees lead to its inclusion in many school profiles (Appel, 2011, p. 85).Generally speaking, bilingual classes can be structured in various ways, causing further confusion by the use of different terms and implementations.It should be noted that this article uses CLIL, bilingual education/classes/lessons, and other terms as synonyms.Further, the conceptual design of bilingual education in Germany, with an emphasis on the federal state of North Rhine-Westphalia, is focused on.
Content and Language Integrated Learning (CLIL) is an accepted teaching approach for bilingual education throughout Europe.It suggests that an additional language is not only used for learning, but for teaching both content and language as well.Content and language are tightly linked, even though the emphasis may shift between the two from time to time.Thus, CLIL can be seen as an innovative form of language and subject teaching, which is closely related to bilingual education and immersion (Coyle, Hood, & Marsh, 2010, p. 1).
Bilingual classes are commonly offered at grammar schools and aimed at middle-class students.Earlier accusations stated that only elite students were offered the opportunity to participate in bilingual education.Nowadays, the recent introduction of bilingual classes in all kinds of primary and secondary schools counters that argument.There are roughly two groups of CLIL students.In one category, there are students who learn parts of their subject in a foreign language (usually English and French, sometimes Spanish).In the second, there are students who speak German as a second language and complete their entire school career in German.The latter case applies to a noticeably higher number of students, for example immigrants, but is not structured as thoroughly as common CLIL classes.This issue gained major importance since 2015, when many refugees came to Germany and when schools decided to integrate these students into so-called "international" or "Welcome" classes in order for them to learn the language of teaching first (for an overview of German practices, see Schmiedebach & Wegner, 2017).
Generally, CLIL is regarded as an additive late partial immersion, as it tends to start in year seven with one subject, and more subjects are added or exchanged later (Breidbach & Viebrock, 2012, p. 6).
In our study's experimental school, history is taught bilingually in year 7, and is substituted for geography and biology in year 8; all three of these subjects make up the bilingual education profile in year 9.In every year, there is a maximum of two bilingual classes and, in order for the students to take part, they must have at least average marks in English (Evangelisch Stiftisches Gymnasium, 2015).This organisation is known as bilingual branches or streams, although there is the possi-bility to offer bilingual modules in individual subjects.In this case, only particular topics are taught in a foreign language over a certain period of time (Breidbach & Viebrock, 2012, p. 6).
Students in bilingual branches usually receive two additional English lessons per week.This sums up to a total of seven lessons, compared to the five lessons their fellow students have.This allows for the enhancement of general-language, subject-specific, and methodological vocabulary (Müller-Schneck, 2006, p. 84).

Current state of research
In order to contrast this study in the context of other types of research on subject-specific knowledge changes, this section will focus on studies that follow the same principles with regard to study focus and design.It will be comprised almost entirely of studies conducted in German schools and will look at the issues of content learning in bilingual programmes and performance assessment.Koch and Bünder (2008) did not find validation for the most common objection that subject-matter learning is inhibited by the use of a foreign language.Supporting findings were consistently confirmed by individuals, but rarely empirically backed up (Koch & Bünder, 2008, p. 4).Therefore, Koch and Bünder (2008) investigated four natural scientific project groups in year five: a German-speaking group, an English-speaking group without experience and two groups that already had bilingual experience from primary school.The materials were adjusted so that language supporting elements were integrated into the lessons.This helped the teacher maintain the foreign language during the whole period, even though monolingualism was not enforced.
Knowledge gain on the content level was evaluated by concept mapping, which is a way of illustrating knowledge structures.The highest increase for content knowledge was recorded for the two test groups with bilingual experience, and the bilingual groups also had a higher learning success than the German control group (Koch & Bünder, 2008, pp. 5-7).Language difficulties may have caused slower communication, but it appears that, as a consequence thereof, the students had a higher attention span and consolidation of knowledge.Without exception, the language problems resulted in a sensitisation and reflection of the learning processes.The authors recommended designing the lessons UNIVERSIDAD DE LA SABANA DEPARTMENT OF FOREIGN LANGUAGES AND CULTURES as action-oriented and communicative, along with the use of written impulses to promote independent work (Koch & Bünder, 2008, p. 7).
In his well-known DEZIBEL project, Zydatiß (2007) surveyed 180 sixteen-year-old students in bilingual branches of grammar schools in Berlin (Zydatiß, 2007, p. 72).He wanted to investigate correlations between linguistic competence (English) and subject-matter abilities in geography, history, and biology.Since his study was carried out at experimental schools, there were no consistent syllabi and the subject knowledge analysis had to focus on "interdisciplinary text and discourse competences."Listening and reading comprehension, text-type bound writing, and the overall use of English was analysed using a proficiency test and an achievement test (Zydatiß, 2007, p. 83).A quarter of the sample took an oral test on language competence.To examine the subject-specific text and discourse competence, a 130-minute test was used which included reading and interpreting non-fictional texts, understanding and applying technical terms, and writing so a certain text-type could be assessed.Background data such as socioeconomic status, Anglophone cultural affinity, and subjective state in the class was collected (Zydatiß, 2007, p. 73).A comparison was drawn between bilingual students that took tests in English and students in the regular programme that had to answer the same tasks in German.Results were consistently positive; in all three competence-based exams bilingual students scored just as good as or higher than the control group.
As expected, their competence level for the English language in listening comprehension, speaking, vocabulary knowledge, and the correct use of written language was distinctly higher when compared to the control group.Regarding subject-specific text and discourse competence, the performance of bilingual and regular students was mostly equal, with some significant differences in favour of the bilingual students, even though to a clearly lower extent than for the language competences (Zydatiß, 2007, p. 320).
A similar study on the students' scientific literacy revealed that bilingual students in biology achieved a distinctly higher competence increase than their monolingual peers (Osterhage, 2007).Scientific literacy is the educational objective of science teaching and therefore reflects the students' subject-specific knowledge.Osterhage (2007)  in Bremen through a 45-minute test.The test contained 18 questions in the areas of "reproduction and sexuality," "respiration and photosynthesis," and "biochemistry and nutrition".All test questions were taken from PISA 2003, an international science test that assesses students' scientific literacy.The author found that bilingual students outperformed their monolingual peers in five competence areas: convergent thinking, number processing, graph processing, mental models, and verbalising facts.He concluded that subject-matter learning is not inhibited in bilingual classes but that other situational circumstances should be considered, such as small classes and additional biology lessons (Osterhage, 2007, pp. 43-47).
When it comes to measuring the performance of bilingual students, Coyle, Hood, and Marsh (2010) suggest three methods for evaluating an increase in content level knowledge.According to the authors, translating a test into the mother tongue is not a reasonable way to collect reliable and comparable data, as tasks requiring detailed answers might be too challenging (Coyle, Hood, & Marsh, 2010, p. 138).A student's understanding should be expressed by other means through the use of graphics, tables, or oral presentations (Coyle, Hood, & Marsh, 2010, p. 138).They also view tests in the mother tongue as a legitimate way of examining students' knowledge, while also admitting that special terms might only have been learned in the CLIL language (Coyle, Hood, & Marsh, 2010, p. 139).A third evaluation method is a portfolio of work, which enables the assessment of different levels of understanding (Coyle, Hood, & Marsh, 2010, p. 139).In our study, we decided to use an English translation of the test; data is relatively comparable as multiple-choice tasks were used and extensive answer texts were not required.In addition, it was decided not to have the test for the bilingual class in their native language because the experimental school's teaching principles require using the target language as much as possible.Kondring and Ewig's (2005) study also addressed the issue of performance assessment in bilingual classes.In general, evaluating students' performance in biology is already difficult, and only gets tougher if it is a bilingual class (Kondring & Ewig, 2005, p. 50).Therefore, the researchers considered whether a similar performance could be expected for bilingual and mainstream students, and in which language the assessments should be carried out (Kondring & Ewig, 2005, p. 50).They investigated UNIVERSIDAD DE LA SABANA DEPARTMENT OF FOREIGN LANGUAGES AND CULTURES two ninth grade classes at a grammar school in North Rhine-Westphalia in a small-scale study.Both classes received an identical teaching unit on the topic 'hearing' by the same teacher.They were assessed via a 20-minute test with mostly closed-form questions (labelling and allocating) and two directional open questions.Only students of the same performance level in both groups were compared; this was established using a record of science and language grades for each student (Kondring & Ewig, 2005, p. 51).An additional survey found that 35-40% of bilingual teachers frequently used multiple-choice questions, which is rarely done in classes only taught in German (Kondring & Ewig, 2005, p. 55).It also appeared that teachers always correct language mistakes in written tests in bilingual courses, even though these mistakes do not influence the assessment (Kondring & Ewig, 2005, p. 56).At least a quarter of the teachers in bilingual classes commonly exchanged views on grading their students (Kondring & Ewig, 2005, p. 58).Results did not show any significant differences in subject-matter performance between bilingual and mainstream students.Instead, there was a slight tendency for regular students to excel the bilingual students performance-wise, as these students supposedly mastered technical terms slightly better (Kondring & Ewig, 2005, p. 59).However, the small sample size does not allow for a representative status (Kondring & Ewig, 2005, p. 58).Our study uses a structure like Kondring and Ewig's study; there is an identical teaching unit for a test and control class, and the type of school and testing procedures were the same.
Similarities can also be found in a study done by Haagen-Schützenhöfer, Mathelitsch, and Hopf (2011) using a bigger sample size.
Since there are nearly no scientifically proven assertions about subject-matter competence, the researchers evaluated bilingual physics classes with regard to the linguistic and content knowledge acquisition of students in the eleventh class.With the help of a pre-and post-test, the learning results of a bilingually taught test group (n = 127) and a control group taught in their native language (n = 78) were compared.
Results demonstrated no apparent differences in content performance of all students.The lack of a significant difference argues against the common opinion that a foreign language impedes subject-specific learning success.However, it should be noted that the teaching unit only consisted of four consecutive physics lessons (Haagen-Schützenhöfer, Mathelitsch, & Hopf, 2011, p. 238ff.).
In addition, Dalton-Puffer (2008) found that CLIL students are able to keep up with monolingually taught peers in subject-matter competence (p.4).She emphasises that a foreign language has the capability to improve the learning of subject-specific concepts.This is closely related to Bonnet's study, which implies that switching to the mother tongue does not solve conceptual problems in the foreign language, but dealing with a concept in L2 can allow for deep semantic processing (as cited in Dalton-Puffer, 2008, p. 142).All the same, performance loss in some students should not be overlooked (Washburn; Nyholm, as cited in Dalton-Puffer, 2008, p. 142).
Lamsfuß-Schenk's ( 2008) study found that ninth grade students taught in a different language were better acquainted with the content knowledge in history than a control group taught in their native language, which may be attributed to dealing more intensively with the learning content (deep processing) (Wolff, 2011, p. 80).Another important factor was an increase in motivation and interest in the topic, leading Wolff to conclude that bilingual education gives the subject new impetus by increasing students' motivation (Wolff, 2011, p. 80).

Problems and fears
A common objection arises when using foreign languages in class, namely that one cannot learn as much as they could in their native language since mastering the subject matter now will take considerably more time.On the other hand, classes getting through the content much faster are not bound to have lasting effects either (Bonnet, Breidbach, & Hallet, 2009, p. 188).
The most common fear reported in parents is that the content level for each lesson will be lowered.Teachers who have not taught bilingual classes yet also share this view (Müller-Schneck, 2006, p. 262).It has been reported that the necessity of language simplification would also entail subject-matter degradation (Müller-Schneck, 2006, p. 262;Hajer, as cited in Dalton-Puffer, 2008, p. 142).Likewise, language problems influence general teaching style, since there is often the need to resort to teacher-centred learning (Pilz, as cited in Müller-Schneck, 2006, p. 262).
In most cases, alleged difficulties can be avoided by using didactic-methodological strategies (Müller-Schneck, 2006, p. 263), e.g., word inference strategies, repeating commonly used phrases for describing and explaining, and also allowing students enough time to gather their thoughts, to talk to their neighbour etc.However, more suitable material (including word annotations, easy vocabulary and alike) must be made available, and teachers should receive special training (Müller-Schneck, 2006, p. 264).This is well demonstrated by studies that have shown that teachers lacking the ability to phrase questions in a way that can address students' individual language performance levels is at least partly responsible for poor subject-matter performance (Yassin, Tek, Alimon, Baharom, & Ying, 2010, p. 52).This creates a dilemma as teachers lower the level of difficulty for both content and language (Yassin et al., 2010, p. 52).One particular study used closed questions without any discussion, and this led to no development of the subject matter (Yassin et al., 2010, p. 52).
From the students' perspective, the benefits of bilingual education are again often experienced differently.A graduate survey of German-French students showed that even in hindsight, 72% thought they had learned at least as much as their monolingually taught peers had.Only 2% admit that they did not learn as much (Landesinstitut Soest, 1995; also see Christ and Krechel, as cited in Müller-Schneck, 2006, p. 270).
Another criticism in respect to bilingual classes is that only linguistically talented students benefit from the concept, but that those who perform well in the topic-related subject and poorer in the language do not (Appel, 2011, p. 85).Another problem is the increasing selection of high-performance students with their parents eager for an optimal academic career (Bonnet, Breidbach, & Hallet, 2009, p. 194).Unfortunately, this observation has to be confirmed in the study at hand.
The school used for the study generally appeals to a rather privileged student body, which is why mostly well-educated students choose the bilingual branch.
Even though some studies (Washburn and Nyholm, as cited in Dalton-Puffer, 2008, p. 142) argue against bilingual education's success, one should be careful about making broad generalisations.This study aims to take a look at the current situation in North Rhine-Westphalia to discover if the contrary is possible.As known, situational conditions and success factors must be taken into account before ultimately deciding on a position, which is too positive or negative (Appel, 2011, p. 87).

Research questions
This study deals with knowledge acquisition in a biology unit taught in German for a control group and in English for a test group.Both groups consisted of year eight students, and the teaching unit focused on the topic of insects.The motivation to conduct this investigation was the feeling that parents' and teachers' constantly express fear that students would not learn in the same depth and speed in bilingual classes as their monolingually taught peers.In contrast to the studies reported earlier (particularly Kondring &Ewig, 2005 andHaagen-Schützenhöfer, Mathelitsch, &Hopf, 2011), this study was spread over 12 lesson-teaching units.This gives us reason to suggest that significantly positive results may be achieved with a longer testing period.Thus, our overarching research question becomes: Is knowledge acquisition in the subject of biology higher in a bilingual class when compared to a regular class?
The research question will be reviewed with the following hypotheses.Initially, it must be guaranteed that students have learned about insects during the teaching unit.For this purpose, there are two hypotheses:

Hypothesis 1a: The control class taught in German shows a significant performance difference between the points of measurement t 1 and t 2 .
Hypothesis 1b: The test class taught in English shows a significant performance difference between the points of measurement t 1 and t 2 .
After the assessment of knowledge acquisition in both classes, differences between the groups will be analysed.As previous studies occasionally found positive effects for bilingual classes, the following hypothesis is presented:

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Hypothesis 2: Knowledge acquisition in the test class is significantly higher than in the control class.Appel (2011) emphasises that only linguistically talented students will benefit from bilingual classes (Appel, 2011, p. 85).Even though the claim for individual learning support also holds true for bilingual education, students with a gift for languages certainly have an advantage.This circumstance will be analysed with the third hypothesis: Hypothesis 3: Students in the test class will show a positive correlation between English performance and knowledge acquisition.
In general, the study targets the analysis of subject-matter acquisition only, since language improvements have been frequently confirmed in previous studies.In addition, these results could help draw conclusions about the suitability of biology as a bilingual subject.

Study design
Fifty students were taken from a year eight in a grammar school in NRW.
Both the test group and control group (n = 25 each) had 12 girls and 13 boys.Throughout the teaching unit, students occasionally missed a lesson, resulting in a final analysis of 44 tests.The test group received their tests in English, whereas the control group took their tests in German; the tests were identical because the English test was a direct translation of the original test.The test group received a vocabulary list that was displayed for everyone on the board.At the end of each test, all students were asked to fill in a short self-evaluation in German.
To determine the suitability of the knowledge test, the questions were given as a pilot test in an eighth grade class that was not part of the actual study.The test was based on 12 lessons that were carried out in both classes.In order for the students not to feel overwhelmed, the usual test duration of 20 minutes was kept by splitting the test into two halves (see Figure 1).Apart from this division for practical reasons, the knowledge test will be regarded as a coherent test instrument.

Knowledge test
The written performance review in this study had to meet certain criteria; the questions must represent different requirement areas, meaning the level of difficulty.This would allow students to receive additional points for the more complex and demanding tasks in higher requirement areas (Berck, 2005, p. 123).Three requirement areas have been established by the Standing Conference of the Ministers of Education and Cultural Affairs of the Federal States in Germany and comprise reproduction, reorganisation, and transfer/problem-solving (Spörhase, 2012, p. 294; see Figure 2).Questions formulated to fit these requirements should touch upon the four competence areas of subject-specific knowledge, knowledge acquisition, evaluation and communication (Kultusministerkonferenz, 2004).Whether a task corresponds to requirement area I, II or III always depends on the previous instruction (Spörhase, 2012, p. 295).

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Due to the special test situation for the study in the school, most tasks were allotted to requirement area I (reproduction), with nearly three times as many tasks in this category compared to reorganisation tasks.The test instrument neglected requirement area III because students had just begun their bilingual biology classes and were not as used to bilingual tests as older students.
There was an imbalance in the thematic distribution of tasks, because the sub units covered different amounts of material; thus, topics that were dealt with lengthily were covered by tasks in both requirement areas, whereas ambiguous topics were made up of only reproduction tasks.A few sample questions (see Table 1) illustrate the type of test and the kind of questions that were asked.

II
Open → short answer A food source is 700 m away from the beehive, at a 40° angle to the left from the position of the sun.Draw the dancing pattern.

II Open → drawing
Source: Own elaboration.
Calculation of the performance difference between t 1 and t 2 is based on the score difference between the two tests.Accordingly, the knowledge gain in the German control class was 16.89 points (SD ± 4.17) and 17.46 points (SD ± 5.52) in the bilingual test class (see Figure 3).As seen in Figure 3, the differences between the pre-and post-tests are significant for both classes (p < .001)(see tables 2 and 3), verifying hypotheses 1a and 1b..000 Source: Own elaboration.
The second hypothesis was concerned with the students' learning success, therefore we analysed whether the test group's knowledge gain was higher than in the control class.As previously mentioned, bilingual students outperformed the control class by 0.57 points in terms of knowledge gain (see Figure 3).However, this result is insignificant, allowing us to discard the second hypothesis.
The third hypothesis suggested that there was a positive correlation between the students' English mark and knowledge acquisition in the bilingual class.The correlation calculation (see Table 4) acknowledges a weak negative but insignificant correlation (r = -.325).The negative correlation values come about by the German marking system, which puts the smallest number (1) as the best mark a student can get, while a higher number (up to 6) is worse.Students with good English marks (1 or 2 on their mid-year report) exhibited an average knowledge gain of 18.29 points, while the weaker students (3 or 4 on their mid-year report) yielded an average knowledge gain of 16.55 points.Although the difference between mean values is insignificant, there was still a tendency for linguistically talented students to experience a slightly higher knowledge gain than their fellow students (see Figure 4).that bilingual students were at a disadvantage in terms of learning the subject matter.These findings coincide with other studies that found that bilingual students did not perform weaker in any of the competence-oriented tests than their fellow students taught in German (Zydatiß, 2007;Kondring & Ewig, 2005;Haagen-Schützenhöfer, Mathelitsch, & Hopf, 2011).These authors interpreted their results as proof that a foreign language does not impede learning success.
Results concerning the second hypothesis could be reinforced by the students' self-evaluation sheets.All students claimed that the post-test was easier to complete, implying that answering the questions was easier, thus some learning process was involved.In addition, the control class considered the test easier, which is presumably due to the fact that the foreign language did not play a role in their situation.
The bilingual students perceived the pre-test as "very difficult" and the post-test as "appropriate," whereas the students taught in German considered the pre-test as only "fairly difficult" and the post-test as "rather easy."The different perception about difficulty is most certainly due to the test group's test being in English and thus including more words they did not know before.Even though many students suspected that the post-and pre-test test would be the same, comments following the post-test advocated content with their answers and that the level of difficulty was adequate.
The third hypothesis proposed a positive correlation between English marks and knowledge acquisition, but had to be falsified due to insignificant results.A moderately negative correlation (r = -.325;due to Germany's marking system, see results) between the students' English mark and knowledge acquisition was observed.The correlation is insignificant, implying that content and pre-knowledge in biology may be more important than profound language skills.However, if chosen to look at the biology mark instead, a different picture emerges.
The difference of approximately one point between the groups may be interpreted when it is assumed that only high-performance students are considered to form a bilingual class.Within the bilingual class, the stronger students experienced a significantly higher knowledge acquisition than the weaker ones.This might be explained because stronger

Conclusion and outlook
Our aim was to investigate the extent to which subject-specific learning would be inhibited by a foreign language-a fear commonly expressed in parents and teachers.It was concluded that both the test and control class exhibited a significant performance difference before and after the teaching unit, implying a knowledge gain.Although the increase was slightly higher in the bilingual class, there was no significant difference in comparison with the control class.
A moderately positive correlation was found between English marks and knowledge gain in bilingual students, although it appeared that their performance in biology was considerably more crucial.Bilingual students good in biology achieved a significantly higher knowledge gain compared to their weaker classmates.This increase in knowledge was still seen in the linguistically weaker student.This may be explained by the fact that the language deficit is compensated by higher levels of motivation and enthusiasm about the subject.
Future studies should include an additional teacher questionnaire to record individual teaching differences (Osterhage, 2007).This is particularly important if lessons are not taught by the same teacher.To expand upon this, the regular teacher should give bilingual classes alone, as an external teacher may be inclined to falsify the intervention by using extra time to settle in and introduce the situation to the students.The class composition must also be taken into consideration, as there may already exist performance differences between bilingual and monolingual students.
Even though one should not jump to the conclusion that teaching bilingual classes is the ne plus ultra, its opportunities should still be recognised and further developed.Bilingual education will continue to be used more extensively in the future, therefore it becomes particularly important to search for improvements.In recent years, investigations have shown various independent methodologies for bilingual classes (Bach, 2001, p. 65).Didactic and methodological developments support an existing established teaching model, but now matters of systematised educational programmes and pedagogical goals become important to keep in mind (Bach, 2001, p. 67).Study designs will also

Figure 1 .
Figure 1.Study set-up with the points in time of respective knowledge tests

Figure 4 .
Figure 4. Graphic display of correlation between the English mark and knowledge acquisition for bilingual students (n=25)

Table 1 .
Sample questions from the knowledge test on (social) insects

Table 2 .
t-Test for differences in test results in the bilingual test class between

Table 3 .
t-Test for differences in test results in the control class between the pre-

Table 4 .
Correlation between English mark and knowledge acquisition for bilingual students(n = 25)

Table 6 .
Correlation between the biology mark and knowledge acquisition for the Source: Own elaboration.

Table 7 .
Correlation between Biology mark and knowledge acquisition for the

Biology mark Knowledge gain in points Biology mark
Source: Own elaboration.