Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 696 · 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.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
2. 2.⚖️ 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
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a magnet (d) a small bowl
6. 6.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) cutting the lemon
7. 7.⚖️ 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 iron setting (d) the kind of juice
8. 8.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
9. 9.🔮 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
10. 10.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
12. 12.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
16. 16.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) plugging in the iron (d) ironing the paper
17. 17.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
19. 19.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
20. 20.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
22. 22.True or false: putting the iron away is a job for an adult. (a) True (b) False
23. 23.⚖️ 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
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) white paper (d) an adult with an iron
25. 25.🧺 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) a balloon
26. 26.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
27. 27.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
29. 29.🍋 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
30. 30.🧺 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) a battery cell (d) white paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a magnet (d) lemon juice
33. 33.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
35. 35.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
37. 37.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ 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
39. 39.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False

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