Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 818 · 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) a small bowl (b) lemon juice (c) a magnet (d) white paper
2. 2.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
3. 3.⚖️ 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) False (b) True
4. 4.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) white paper (d) a cotton bud
7. 7.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice (d) the same paper
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) an adult with an iron (d) yeast
10. 10.⚖️ 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 keep it the same (c) we measure it
11. 11.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
13. 13.⚖️ 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
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
16. 16.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
17. 17.True or false: letting the paper dry is a job a child can do. (a) False (b) True
18. 18.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) ironing the paper
19. 19.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
20. 20.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) turmeric powder
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) a cotton bud (d) lemon juice
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
24. 24.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a balloon
27. 27.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
28. 28.True or false: plugging in the iron is a job for an adult. (a) True (b) False
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a mirror (d) a battery cell
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
35. 35.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a mirror (d) a small bowl
37. 37.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) plugging in the iron
38. 38.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: cutting the lemon is a job a child can do. (a) False (b) True
40. 40.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed

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