Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 713 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
4. 4.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) plugging in the iron (d) dipping the cotton bud
5. 5.True or false: plugging in the iron is a job for an adult. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) an adult with an iron
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
8. 8.True or false: reading the message is a job a child can do. (a) True (b) False
9. 9.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) paper turns lemony (d) heat adds colour
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
13. 13.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
14. 14.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) a small bowl (d) a balloon
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the same cotton bud (d) the iron setting
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a battery cell (d) a cotton bud
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) lemon juice (d) an adult with an iron
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the kind of juice (c) the ironing time (d) how dark the writing is
21. 21.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the iron setting
25. 25.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) reading the message (d) cutting the lemon
26. 26.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
27. 27.True or false: plugging in the iron is a job a child can do. (a) True (b) False
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) almost nothing (d) a rainbow
29. 29.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
31. 31.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a mirror (d) white paper
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) lemon juice (d) a magnet
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
40. 40.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a cotton bud (d) a mirror

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