Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 468 · 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? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) letting the paper dry (d) cutting the lemon
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
5. 5.⚖️ 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 keep it the same (c) we change it
6. 6.True or false: plugging in the iron is a job for an adult. (a) False (b) True
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
8. 8.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
11. 11.⚖️ 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
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) a small bowl
13. 13.⚖️ 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 measure it (c) we keep it the same
14. 14.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) cutting the lemon (d) plugging in the iron
15. 15.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) putting the iron away
16. 16.True or false: putting the iron away is a job for an adult. (a) True (b) False
17. 17.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) writing the message (d) reading the message
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
19. 19.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
20. 20.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
22. 22.⚖️ 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 measure it (c) we change it
23. 23.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) putting the iron away
24. 24.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
26. 26.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) ironing the paper
27. 27.True or false: ironing the paper is a job a child can do. (a) False (b) True
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a battery cell (d) turmeric powder
29. 29.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
30. 30.True or false: plugging in the iron is a job a child can do. (a) True (b) False
31. 31.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
32. 32.True or false: ironing the paper is a job for an adult. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
34. 34.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
35. 35.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) lemon juice (d) white paper
37. 37.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) yeast (d) white paper
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a balloon (d) an adult with an iron

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