Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 565 · 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 a balloon for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
3. 3.⚖️ 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 change it (c) we keep it the same
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) a small bowl (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the iron setting (d) the same paper
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
9. 9.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
15. 15.True or false: ironing the paper is a job a child can do. (a) True (b) False
16. 16.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
17. 17.⚖️ 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
18. 18.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the ironing time
20. 20.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) lemon juice (d) white paper
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) yeast (d) turmeric powder
23. 23.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) plugging in the iron
24. 24.True or false: white paper is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) a battery cell (d) a mirror
26. 26.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
27. 27.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
28. 28.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
29. 29.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) dipping the cotton bud (d) reading the message
30. 30.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
31. 31.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
33. 33.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) writing the message
34. 34.True or false: writing the message is a job a child can do. (a) True (b) False
35. 35.⚖️ 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 same cotton bud (c) the kind of juice
36. 36.⚖️ 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 measure it (c) we change it
37. 37.⚖️ 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) False (b) True
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: letting the paper dry is a job for an adult. (a) True (b) False

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