‘But, is it supposed to be a straight line?’ Scaffolding students’ experiences with pressure sensors and material resistance in a high school biology classroom

Figures & data

Figure 1. The experimental setup with the potato and pressure sensor [left] and an illustration of this in the module [right].

Table 1. Timeline of classroom implementation. The * represents the analysed portion of the case study. Students also took pre/post assessments (1 class day for each).

Date	Investigations	Collected data
Unit 1 – October 2019, 5 class days	Enzyme function lab with glucose metres, introductory unit	Pretest, video recordings of whole class, screencasts, fieldnotes based on in-person observations, digital artefacts of student work
Unit 2 – November-December 2019, 11 class days	Potato osmosis with pressure sensors, 5 class days* Diffusion simulations, 6 class days	Video recordings of whole class, screencasts, in person observations, digital artefacts of student work, photographs of students’ ‘Do Now’ activity
Unit 3 – January 2020, 6 class days	Independent lab/photosynthesis	Video recordings of whole class, screencasts, in person observations, digital artefacts of student work

Table 2. Instances of students asking questions about the data and how adults scaffolded student questions.

Instance	The support that adults opted to offer
Students asked if the data ‘is going’ (can’t see the line at current scale)	Curriculum developer verified that the data ‘is going’
Students asked ‘is this supposed to be a straight line’	Observer provided a reflective toss
Students did not recognise their own data, rescaled and in different representation	Teacher responded ‘in all of these I have made it bigger’ and then redirected attention to experimental procedure
Students rescaled graph by mistake and asked for help re-configuring graph	Observer proceeded to fix technical issue

Figure 2. A representative graph showing what students saw when they were collecting data on the first day about 45 s after data collection started.

Note: This is a recreation.

Figure 3. The teacher rescaled the data to show the correct scale, but the students did not seem to recognise their data when it was projected on the board.

Note: The graph was recreated by the authors from the same student data table and scaled to match the image from classroom video.

Figure 4. The graph that the students produced when they seem to have accidentally rescaled the data before the first author approached the group. The graph oscillates, jumping between two values that represent miniscule changes in pressure, because the sensor is approaching its resolution limit.

Figure 5. What was on screen on Day 2 when the researcher/first author approached the group. Note the small ‘bump’ at approximately 160 s.

Figure 6. The graphs that the students produced with a simulation that explores diffusion across a cellular membrane.