Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 755 · 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 same paper is what we measure. (a) True (b) False
2. 2.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
3. 3.⚖️ 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
4. 4.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) turmeric powder (d) a battery cell
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) white paper (d) a small bowl
8. 8.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
10. 10.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
12. 12.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
13. 13.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
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 same cotton bud
15. 15.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
18. 18.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is sticky (d) it is cold
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) an adult with an iron (d) a battery cell
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a magnet (d) white paper
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
24. 24.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a magnet
26. 26.⚖️ 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
27. 27.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) putting the iron away (d) reading the message
28. 28.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
29. 29.True or false: putting the iron away is a job a child can do. (a) False (b) True
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a mirror (d) lemon juice
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
36. 36.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) turmeric powder (d) a small bowl
37. 37.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
38. 38.⚖️ 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 keep it the same (c) we measure it
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
40. 40.True or false: reading the message is a job for an adult. (a) False (b) True

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