Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 167 · 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.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) a small bowl
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) how dark the writing is (d) the kind of juice
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) how dark the writing is (d) the same cotton bud
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) a small bowl (d) lemon juice
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) an adult with an iron (d) turmeric powder
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
9. 9.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ 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
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a cotton bud (d) a small bowl
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
15. 15.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
16. 16.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
18. 18.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
19. 19.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) white paper (d) a cotton bud
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) cutting the lemon
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
26. 26.True or false: putting the iron away is a job for an adult. (a) True (b) False
27. 27.True or false: putting the iron away is a job a child can do. (a) False (b) True
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
30. 30.True or false: writing the message is a job for an adult. (a) False (b) True
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) lemon juice (d) yeast
34. 34.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) reading the message (d) dipping the cotton bud
36. 36.True or false: letting the paper dry is a job for an adult. (a) True (b) False
37. 37.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
39. 39.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
40. 40.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it

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