Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 782 · 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 “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.⚖️ 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
3. 3.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) yeast (d) a balloon
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a mirror (d) a small bowl
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the ironing time
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
9. 9.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) brown (d) white
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
12. 12.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a battery cell (d) white paper
14. 14.⚖️ 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) False (b) True
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
16. 16.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
17. 17.True or false: plugging in the iron is a job for an adult. (a) False (b) True
18. 18.True or false: letting the paper dry is a job for an adult. (a) False (b) True
19. 19.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) turmeric powder (d) a cotton bud
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
23. 23.True or false: writing the message is a job a child can do. (a) False (b) True
24. 24.True or false: cutting the lemon is a job a child can do. (a) True (b) False
25. 25.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
27. 27.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
28. 28.⚖️ 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) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a magnet (d) an adult with an iron
30. 30.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) reading the message
32. 32.⚖️ 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
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
34. 34.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
36. 36.⚖️ 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
37. 37.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
38. 38.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it

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