Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 126 · 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? Which of these is the one thing we change? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is (d) the same paper
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
3. 3.True or false: cutting the lemon is a job for an adult. (a) True (b) False
4. 4.⚖️ 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 paper (c) the kind of juice
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
6. 6.True or false: reading the message is a job for an adult. (a) True (b) False
7. 7.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a magnet
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a cotton bud (d) a mirror
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
11. 11.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
13. 13.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a small bowl (d) white paper
15. 15.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
16. 16.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) putting the iron away (d) ironing the paper
17. 17.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
18. 18.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) white (d) green
20. 20.⚖️ 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 change it (c) we keep it the same
21. 21.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
22. 22.True or false: letting the paper dry is a job for an adult. (a) True (b) False
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a balloon (d) white paper
24. 24.True or false: ironing the paper is a job a child can do. (a) False (b) True
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) yeast (c) white paper (d) an adult with an iron
26. 26.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
27. 27.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
28. 28.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
29. 29.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
30. 30.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
32. 32.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
34. 34.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a magnet (c) an adult with an iron (d) lemon juice
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the ironing time (c) the same paper (d) how dark the writing is
38. 38.⚖️ 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
39. 39.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold

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